Question

Solve using elimination.

8x − 8y = –8
9x − 7y = 11

Answer 1

Multiply the first equation by 9 and the second by −8 to eliminate x:

9(8x − 8y) = 9(−8) → 72x − 72y = −72
−8(9x − 7y) = −8(11) → −72x + 56y = −88

Add the two equations:
(72x − 72y) + (−72x + 56y) = −72 + (−88)
−16y = −160 → y = 10

Substitute y = 10 into 8x − 8y = −8:
8x − 80 = −8 → 8x = 72 → x = 9

Solution: (x, y) = (9, 10).