Answer:
x = -4
y = -3
Explanation:
-4x + 4y = 4 Eq. 1
y = 3x + 9 Eq. 2
Replacing Eq. 2 in Eq. 1:
-4x + 4(3x+9) = 4
-4x + (4*3x + 4*9) = 4
-4x + (12x+ 36) = 4
8x + 36 = 4
8x = 4 - 36
8x = -32
x = -32/8
x = -4
From Eq. 2
y = 3*-4 + 9
y = -12 + 9
y = -3
Check:
From Eq. 1
-4x + 4y = 4
-4*-4 + 4*-3 = 4
16 - 12 = 4