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Lesson 1: Intro to rates

# Rate review

Review the basics of rates and try some practice problems.

## What is a rate?

A rate is a ratio that compares two quantities with different units of measure.
Example of a rate:
A plane flew $765$ kilometers in $3$ hours.

### Unit rates

A unit rate of two quantities in a ratio is the number of units of the first quantity for every $1$ unit of the second quantity.
Examples of unit rates:
There are $60$ minutes in $1$ hour.
Jen types $42$ words in $1$ minute.

## Finding unit rates

To find a unit rate, we divide the first quantity in a rate by the second.
Example:
A plane flew $765$ kilometers in $3$ hours.
$765÷3=255$
The plane flew at a rate of $255$ kilometers per hour. We can also write the unit rate as .

## Using unit rates to solve rate problems

Let's look at an example.
Mark can make $42$ birthday cakes in $7$ days.
How many birthday cakes can Mark make in $5$ days?
First, we find the unit rate.
DaysCakes
$7$$42$
$↓÷7$$↓÷7$
$1$$6$
Mark makes cakes at a unit rate of $6$ cakes for every $1$ day.
Now, we can use the unit rate to find how many cakes Mark makes in $5$ days.
DaysCakes
$7$$42$
$1$$6$
$↓×5$$↓×5$
$5$$30$
In $5$ days, Mark can make $30$ cakes.

## Practice

Problem 1
Frances can complete $91$ oil changes in $7$ days.
How many oil changes can Frances complete in $11$ days?
oil changes

Want to try more problems like this? Check out this exercise.