y
=
y=
3
x
+
28
3x+28
y
=
y=
−
4
x
−4x

Replace y = -4x into y = 3x + 28
-4x = 3x + 28
Minus both side by 3x
-7x = 28
x = -4
Recheck : - 4 x (-4) = 3 x (-4) + 28
16 = -12 +28 = 16 (t)
Answer:
(- 4, 16 )
Step-by-step explanation:
y = 3x + 28 → (1)
y = - 4x → (2)
substitute y = 3x + 28 into (2)
3x + 28 = - 4x ( add 4x to both sides )
7x + 28 = 0 ( subtract 28 from both sides )
7x = - 28 ( divide both sides by 7 )
x = - 4
substitute x = - 4 into (2)
y = - 4(- 4) = 16
solution is (- 4, 16 )