CPM Homework Help : CCG Problem 8-89

Multiple Choice: What is the solution to the system of equations at right?

$\begin{array}{c} y = \frac { 1 } { 2 }x - 4 \\ x - 4y = 12 \end{array}$

Step 1:

First solve the bottom equation for $y$ .

$4y=x-12$ , so $y=\frac{1}{4}x-3$

Step 2:

Now set the two equations equal to each other.

$\frac{1}{2}x-4=\frac{1}{4}x-3$

Step 3:

Now solve for $x$ .

$\frac{1}{4}x=1$

Answer:

$x=4$ , so D