Answer:
x = -7
y = -30
Explanation:
y = 3x - 9 (1)
y = 6x + 12 (2)
by subtracting equation (1) from equation (2)
y = 6x + 12
y = 3x - 9
- - +
_________
0 = 3x + 21
3x = -21
x = -21/3 = -7
by substituting value of x in equation (1)
y = 3(-7) - 9
= -21 - 9 = -30