Question

3x – 7y = 5
9y = 5x + 5
A.
(–3, 2)
B.
(8, 5)
C.
(–10, –5)
D.
(0, 0)

Answer 1

3x - 7y = 5
y = 5/9 x + 5/9

3x - 7(5/9 x + 5/9) = 5
3x - 35/9 x - 35/9 = 5
3x - 35/9x = 35/9 + 5
3x - 35/9x = 80/9
-8/9 x = 80/9

Multiply both sides by the reciprocal.
x = (80/9)(9/-8)
x = -10

3(-10) -7y = 5
-30 -7y = 5
-7y = 35
y = -5

Answer: c. (–10, –5)