Question

Solve using substitution. 7x-4y=-12 9x-4y=-20

Answer 1

Answer:y= -4

Step-by-step explanation:

1 Solve for xx in 7x-4y=-127x−4y=−12.

x=\frac{4(y-3)}{7}

x=

7

4(y−3)

​

2 Substitute x=\frac{4(y-3)}{7}x=

7

4(y−3)

​

 into 9x-4y=-209x−4y=−20.

\frac{36(y-3)}{7}-4y=-20

7

36(y−3)

​

−4y=−20

3 Solve for yy in \frac{36(y-3)}{7}-4y=-20

7

36(y−3)

​

−4y=−20.

y=-4

y=−4

4 Substitute y=-4y=−4 into x=\frac{4(y-3)}{7}x=

7

4(y−3)

​

.

x=-4

x=−4

5 Therefore,

\begin{aligned}&x=-4\\&y=-4\end{aligned}

​

 

x=−4

y=−4

​