Answer:
x= -4 and y = -15
Step-by-step explanation:
To solve this problem, we will follow the steps below;
y = 3/4 x - 12 ___________________________________(1)
y = -4x - 31 _____________________________________(2)
substitute equation (1) in equation (2)
3/4 x - 12 = -4x - 31
Add 4x to both-side of the equation
3/4 x + 4x - 12 = -4x + 4x - 31
3/4 x + 4x - 12 = - 31
Add 12 to both-side of the equation
3/4 x + 4x - 12 + 12 = - 31 + 12
3/4 x + 4x = - 31 + 12
[tex]\frac{3x + 16x}{4}[/tex] = -19
[tex]\frac{19x}{4}[/tex] = -19
Multiply 4 to both-side of the equation
[tex]\frac{19x}{4}[/tex] × 4 = -19 × 4
At the left-hand side of the equation, 4 will cancel-out 4, thus the equation becomes;
19x = -19 × 4
Divide both-side of the equation by 19
[tex]\frac{19x}{19}[/tex] = [tex]\frac{-19 X 4}{19}[/tex]
(On the left-hand side of the equation 19 at the numerator will cancel out 19 at the denominator leaving us with just x, likewise, on the right-hand side of the equation 19 at the numerator will also cancel-out 19 at the denominator leaving us with -4)
x = -4
Substitute x = -4 into equation (2)
y = -4x - 31
y = -4(-4) - 31
= 16 - 31
=-15
y=-15
x= -4 and y = -15
