# How do you solve by substitution 2x-y=23 and x-9=-1?

##### 1 Answer
Apr 25, 2018

We write the second equation $x = 9 - 1 = 8$ and substitute into the first: $2 \left(8\right) - y = 23$ or $y = 2 \left(8\right) - 23 = - 7$.

#### Explanation:

Check $x = 8 , y = - 7$

 2(8) - (-7) = 16 + 7 = 23 quad sqrt

 8 - 9 = -1 quad sqrt