2x - 3y = -7
x + 4y = 2 ⇒ x = 2 - 4y
2 × (2 - 4y) - 3y = -7
4 - 8y - 3y = -7
4 - 11y = -7
11y = 4 - (-7)
11y = 4 + 7
11y = 11
y = 11 : 11
y = 1
x = 2 - 4 × 1
x = 2 - 4
x = -2
S = {(-2, 1)}