# How do you solve the system of equations -7x + 5y = - 21 and - x + y = - 5?

Apr 11, 2018

The solution is $x = - 2$ and $y = - 7$.

#### Explanation:

I will show you how to solve this problem using the substitution method.

From the second equation we can write:

$y = x - 5$

And then we plug $y$ into the first equation:

$- 7 x + 5 \cdot \left(x - 5\right) = - 21$

$- 7 x + 5 x - 25 = - 21$

$- 2 x = 4$

$x = - 2$

At the end we solve $y = x - 5$:

$y = - 2 - 5$

$y = - 7$