# How do you solve 2x-y=7 and 3x+y=8?

Dec 1, 2015

$x = 3$, $y = - 1$

#### Explanation:

From the first equation, you know that $y = 2 x - 7$. Substitute this expression for $y$ in the second equation and get

$3 x + \left(2 x - 7\right) = 8$

$5 x - 7 = 8$

$5 x = 15$

$x = 3$

Once $x$ is known, we can derive $y$ from

$y = 2 x - 7 = 2 \cdot 3 - 7 = 6 - 7 = - 1$