Question

“Stephen attempted to use the elimination method to solve the system of equations below but he made a mistake. What is it?

Answer 1

second option

Explanation:

x + y = 18 → (1)

4x - 3y = - 12 → (2)

Multiplying (1) by - 4 and adding to (2) will eliminate the x- term

- 4x - 4y = - 72 → (3)

add (2) and (3) term by term to eliminate x

0 - 7y = - 84

- 7y = - 84 ( divide both sides by - 7 )

y = 12

Substitute y = 12 into (1) and solve for x

x + 12 = 18 ( subtract 12 from both sides )

x = 6

solution is x = 6, y = 12