2x-3y+8=20 4x+2y-7=13

2x-3y=20-8
2x-3y=12

4x+2y=13+7
4x+2y=20

2x - 3y = 12 (×2)
4x + 2y = 20 (×1)

4x - 6y = 24
4x + 2y = 20
-------------------- -
-8y = 4
y = 4/-8
y = -1/2

2x - 3y = 12
2x - 3(-1/2) = 12
2x + 3/2 = 12
2x = 12 - 3/2
-2x = 24/2 - 3/2
2x = 21/2
x = (21/2)/2
x = 21/2 × 1/2
x = 21/4
x = 5 1/4

Jadi himpunan penyelesaiannya adalah {(5 1/4 , -1/2)}