Question

Solve using elimination.

3x − 5y = –18
–3x + 4y = 9

Answer 1

Add the equations to eliminate x:
(3x − 5y) + (−3x + 4y) = −18 + 9
−y = −9 ⇒ y = 9.

Substitute y = 9 into 3x − 5y = −18:
3x − 45 = −18 ⇒ 3x = 27 ⇒ x = 9.

Solution: x = 9, y = 9. (Check: 3·9 − 5·9 = 27 − 45 = −18 and −3·9 + 4·9 = −27 + 36 = 9.)