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## 8th grade (Eureka Math/EngageNY)

### Course: 8th grade (Eureka Math/EngageNY) > Unit 4

Lesson 4: Topic D: Systems of linear equations and their solutions- Systems of equations: trolls, tolls (1 of 2)
- Systems of equations: trolls, tolls (2 of 2)
- Testing a solution to a system of equations
- Solutions of systems of equations
- Systems of equations with graphing
- Systems of equations with graphing
- Systems of equations with graphing: 5x+3y=7 & 3x-2y=8
- Systems of equations with graphing: y=7/5x-5 & y=3/5x-1
- Systems of equations with graphing: chores
- Systems of equations with graphing
- Systems of equations with elimination: 3t+4g=6 & -6t+g=6
- Systems of equations with elimination
- Systems of equations with elimination: x+2y=6 & 4x-2y=14
- Systems of equations with elimination: -3y+4x=11 & y+2x=13
- Systems of equations with elimination: 2x-y=14 & -6x+3y=-42
- Systems of equations with elimination: 4x-2y=5 & 2x-y=2.5
- Systems of equations with elimination: x-4y=-18 & -x+3y=11
- Systems of equations with elimination
- Systems of equations with elimination: 6x-6y=-24 & -5x-5y=-60
- Systems of equations with elimination challenge
- Systems of equations with substitution: 2y=x+7 & x=y-4
- Systems of equations with substitution
- Systems of equations with substitution: y=4x-17.5 & y+2x=6.5
- Systems of equations with substitution: -3x-4y=-2 & y=2x-5
- Systems of equations with substitution: 9x+3y=15 & y-x=5
- Systems of equations with substitution
- Systems of equations with substitution: y=-5x+8 & 10x+2y=-2
- Systems of equations with substitution: y=-1/4x+100 & y=-1/4x+120
- Systems of equations with elimination: apples and oranges
- Systems of equations with elimination: TV & DVD
- Systems of equations with elimination: King's cupcakes
- Systems of equations with elimination: Sum/difference of numbers
- Systems of equations with elimination: potato chips
- Systems of equations with elimination: coffee and croissants
- Systems of equations with substitution: coins
- Systems of equations with substitution: potato chips
- Systems of equations with substitution: shelves
- Systems of equations word problems
- Age word problem: Imran
- Age word problem: Ben & William
- Age word problem: Arman & Diya
- Age word problems
- Solutions to systems of equations: consistent vs. inconsistent
- Systems of equations number of solutions: fruit prices (1 of 2)
- Systems of equations number of solutions: fruit prices (2 of 2)
- Systems of equations number of solutions: y=3x+1 & 2y+4=6x
- Solutions to systems of equations: dependent vs. independent
- Number of solutions to a system of equations graphically
- Number of solutions to a system of equations graphically
- Forming systems of equations with different numbers of solutions
- Number of solutions to a system of equations algebraically
- Comparing Celsius and Fahrenheit temperature scales
- Converting Fahrenheit to Celsius

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# Comparing Celsius and Fahrenheit temperature scales

Comparing Celsius and Fahrenheit temperature scales. Created by Sal Khan and Monterey Institute for Technology and Education.

## Want to join the conversation?

- how would you say 30 celsius in farenheit?(21 votes)
- Another way of convert C to F without having to divide follows:

EX 1: 1500 C = ? F Multiply 1500 by 2 = 3000

Take 10% of 3000 = 300

Subtract 300 from 3000 = 2700

Add 32 to 2700 = 2732 F

Ex 2: 100 C = ? F 100 x2 =200

10% of 200 = 20

200 – 20 = 180

180+32 = 212 F(12 votes)

- If 0 Celsius = 32 Farenheit

Why 100 Celsius = 212 Farenheit? it must be 132 Farenheit.(11 votes)- The Celsius and Fahrenheit scales do not have the same difference. That is, going up one degree in Celsius is not the same as going up one degree in Fahrenheit. In fact, going up one degree in Celsius means going up 9/5 degrees in Fahrenheit. (You can calculate the formula using the points for freezing point and boiling point.)(11 votes)

- at about0:45he says at standard pressure, I didn't know that pressure mattered, does it raise the freezing point or lower the freezing point?(8 votes)
- Not only pressure but solutes can affect the boiling/freezing points as well. I'm not sure what school year you're in but I learned it in high school. If you're not in high school yet, here's a place for a detailed early lesson.

http://www.animations.physics.unsw.edu.au/jw/freezing-point-depression-boiling-point-elevation.htm(7 votes)

- Is the word "Farenheit" an acceptable alternative to "Fahrenheit" in the English language or is mostly everyone on this page, including the title and the context of the video (when Sal writes it), misspelling "Fahrenheit"?(6 votes)
- As far as I know, Fahrenheit is the only authoritative form of the word, however Farenheit is an often-made mistake.(7 votes)

- At1:00, why is the Celsius scale called the Celsius scale and why is the Fahrenheit scale called the Fahrenheit scale?(3 votes)
- Fahrenheit (symbol °F) is a temperature scale based on one proposed in 1724 by the physicist Daniel Gabriel Fahrenheit.

Eighteen years later In 1742, Swedish astronomer Anders Celsius (1701–1744) created a temperature scale which was the reverse of the scale now known by the name "Celsius": 0 represented the boiling point of water, while 100 represented the freezing point of water.(3 votes)

- on the Celsius scale what temperature is 48 above the freezing point of water(2 votes)
- Interestingly, water freezes at 0°C. So 48°C is 48° above freezing.(3 votes)

- why are the freezing and boiling temperatures (in Fahrenheit) pretty much based on random numbers unlike Celsius.(2 votes)
- It does seem odd at first. On Wikipedia there is an interesting description of the history of the Fahrenheit scale.

If I understand correctly, Fahrenheit is related to another temperature scale that was based on the freezing point of a saltwater solution. There was some creative thought put into defining the degree scale.

I feel Celsius is much easier to use and understand, but history is a powerful thing.(3 votes)

- The celcius is multiply by 9 and then divided in 5 plus 32(3 votes)
- How do u change farihiet to celsius(2 votes)
- hello can you expain why the US uses farenheit still, is it because for electronics work etc... heat can be measured to a finer degree? (no pun intended)(2 votes)

## Video transcript

Look at the two thermometers
below. Identify which is Celsius and
which is Fahrenheit, and then label the boiling and freezing
points of water on each. Now, the Celsius scale
is what's used in the most of the world. And the easy way to tell that
you're dealing with the Celsius scale is on the Celsius
scale, 0 degrees is freezing of water at standard
temperature and pressure, and 100 degrees is the boiling point
of water at standard temperature and pressure. Now, on the Fahrenheit scale,
which is used mainly in the United States, the freezing
point of water is 32 degrees, and boiling of water
is 212 degrees. As you could tell, Celsius,
the whole scale came from using freezing as 0 of regular
water at standard temperature and pressure and setting
100 to be boiling. On some level, it makes a little
bit more logical sense, but at least here in the U.S.,
we still use Fahrenheit. Now let's figure out which of
these are Fahrenheit and which are Celsius. Now remember, regardless of
which thermometer you're using, water will always
actually boil at the exact same temperature. So Fahrenheit, 32 degrees, this
has to be the same thing as Celsius 0 degrees. So let's see what happens. So when this temperature right
here is 0, this one over here, it looks like it's negative
something. So this one right here doesn't
look like Celsius. Here, if we say this is Celsius,
this looks pretty close to 32 on this one. Let me do that in
a darker color. So this one right here looks
like Celsius, and this one right here looks like
Fahrenheit. And the way I was able to tell
is that the 0 degrees Celsius needs to be the same thing
as 32 degrees Fahrenheit. In both cases, this is
where water freezes, the freezing point. That is water freezing. And let's make sure
we're right. So if this is the Celsius scale,
this is where water will boil, 100 degrees Celsius,
and that looks like it is right about 212
on the other scale. So right there is where water
is boiling at standard temperature and pressure. So this thing on the right,
right here, I guess I'll circle it in orange,
that is Celsius. And then the one on the left,
I'll do it in magenta, the one on the left is Fahrenheit.