Before starting out on a road trip you fill the gas tank with 11 gallons of gas. After driving 58 miles you check the gas gauge and know that you have 9 gallons left.

Question

What is your rate (slope)? __ miles per gallon

how many miles can be driven in 4 gallons? __ miles

how many miles would you have driven if there was only 5 gallons left in the gas tank? __ miles

Answer 1

First find the slope = y₂ - y₁/x₂ - x₁ given (11, 0) and (9, 58)

m = (58 - 0)/(9 - 11) = 58/-2 = -29

The slope is -29 miles per gallon, so we know that we lose 1 gallon of gas for every 29 miles that are driven.

To find how many miles can be driven in 4 gallons we can take the rate and multiply it by gallons:

29(4) = 116 miles

If there are only 5 gallons left, then 11 - 5 = 6 gallons were used:

29(6) = 174 miles