Unit 2, Lesson 9
Which Variable to Solve for? (Part 2)
Algebra 1
Practice
Problem 1
A car has a 16-gallon fuel tank. When driven on a highway, it has a gas mileage of 30 miles per gallon. The gas mileage (also called "fuel efficiency") tells us the number of miles the car can travel for a particular amount of fuel (one gallon of gasoline, in this case). After filling the gas tank, the driver got on a highway and drove for a while.
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How many miles has the car traveled if it has the following amounts of gas left in the tank?
- 15 gallons
- 10 gallons
- 2.5 gallons
- Write an equation that represents the relationship between the distance the car has traveled in miles, \(d\), and the amount of gas left in the tank in gallons, \(x\).
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How many gallons are left in the tank when the car has traveled the following distances on the highway?
- 90 miles
- 246 miles
- Write an equation that makes it easier to find the the amount of gas left in the tank, \(x\), if we know the car has traveled \(d\) miles.
Problem 2
The area \(A\) of a rectangle is represented by the formula \(A = lw\) where \(l\) is the length and \(w\) is the width. The length of the rectangle is 5.
Write an equation that makes it easy to find the width of the rectangle if we know the area and the length.