Question

The Zepeda family filled the gasoline tank of their minivan at the beginning of a long trip. The relationship between the number of miles driven and the number of gallons remaining in the tank can be modeled with a linear function. When they had driven 120 miles, there were 18 gallons of gasoline in the tank. When they had driven 300 miles, only 6 gallons were left in the tank. How many miles could the Zepedas drive before running out of gasoline?

Answer 1

If we model the situation as

y = mx+b

then we have

120m+b = 18
300m+b = 6
Subtract to get
-180m = 12
m = -1/15
So, b = 26

y = -1/15 x + 26

y=0 when x = 390