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### Course: 8th grade (Illustrative Mathematics)>Unit 3

Lesson 2: Lesson 4: Comparing proportional relationships

# Rates & proportional relationships: gas mileage

Maria and Nadia calculate their speed on a road trip to Toronto using distance and time. We compare different speeds using equations and tables. Then, we reinforce the concept by comparing the revolution speeds of records. Created by Sal Khan.

## Want to join the conversation?

• i still do not understand it how did he get 60mph from 4 hours and 240 miles.
• Think about how mph means "miles per hour" - you can write it in fraction form like this:

miles
-------
hour

Now, let's take the given information (4 hours & 240 miles) and plug the numbers into this fraction:

240 miles
------------- = 240 / 4 miles per hour = 60 mph
4 hours

Hope this helps!
• I get confused sometimes. Is the coefficient x, Or is the number 65 the coefficient? I find it difficult to tell which one is which sometimes, I just don't really understand or think that it makes very much sense.
• 65 is the coefficient (the number before the variable).
• Is the coefficient x or y
• Neither x nor y is the coefficient.
• I dont get it :,D?
• wait a minute. . . I forgot how this works!! but I won't give up.
• can you show me more about graphs
• i still do not understand it how did he get 60mph from 4 hours and 240 miles.
• He divided 240 by 4 to find the average. Since mph is "miles per hour" dividing the 4 hours by 4 let's us find the value equivalent to 1 hour, and to find the average we divide the 240 by 4 as well, which equals 60(mph).
• I don't understand
• What does revolution mean?
Please make it easy for me to understand^^;
thanks!