Question

HELP PLEASE???!!!!!!!

What is the solution to the system of equations below?


y=3/4x-12 and y=-4x-31


A. (–4, –15)

B. (–4, –12)

C. (4, –9)

D. (4, –47)

Answer 1

A. (-4, -15)

Explanation:

`\left\{\begin{array}{ccc}y=(3)/(4)x-12&(1)\\y=-4x-31&(2)\end{array}\right\\\\\text{Substitute (1) to (2):}\\\\(3)/(4)x-12=-4x-31\qquad\text{multiply both sides by 4}\\\\3x-48=-16x-124\qquad\text{add 48 to both sides}\\\\3x=-16x-76\qquad\text{add}\ 16x\ \text{to both sides}\\\\19x=-76\qquad\text{divide both sides by 19}\\\\x=-4\\\\\text{Put it to (2):}\\\\y=-4(-4)-31\\y=16-31\\y=-15`