Question

Felix needs to find x and y in the following system:

Equation A: 7y - 4x = 5
Equation B: 3y + 4x = 25
If he wants to use the elimination method to eliminate one of the variables, which is the most efficient way for him to do so?

A. Add Equation A and Equation B

B. Subtract Equation B from Equation A

C. Multiply Equation A by 5.

D. Divide Equation B by -1.

Answer 1

A. Add Equation A and Equation B.

Explanation:

When you add Equation A and Equation B, you'd get (when combining like terms)

(7y + 3y) + (-4x + 4x) = (5 + 25), which becomes 10y = 30

This show us that adding the equations allows us to cancel (eliminate) the x variable. Then we'd solve for y and later we'd solve for x by plugging in the value for y into either equation A or equation B.