SAT Math Multiple Choice Question 508: Answer and Explanation
13. What was the initial amount of gasoline in a fuel trailer, in gallons, if there are now x gallons, y gallons were pumped into a storage tank, and then 50 gallons were added to the trailer?
- A. x + y + 50
- B. x + y - 50
- C. y - x + 50
- D. x - y - 50
Correct Answer: B
Category: Heart of Algebra / Linear Equations
Strategic Advice: Write an equation in words first and then translate from English to math. Finally, rearrange your equation to find what you're interested in, which is the initial amount of gasoline.
Getting to the Answer: Call the initial amount A. After you've written your equation, solve for A.
Amount now (x) = Initial amount (A) minus y, plus 50
x = A - y + 50
x + y - 50 = A
The initial amount was x + y - 50 gallons. Note that you could also use Picking Numbers to answer this question.