# How do you solve 3x+y=9 and 2x+y=4?

Aug 2, 2015

Subtract the second equation from the first to get $x = 5$, then substitute that into either equation and rearrange to find $y = - 6$

#### Explanation:

Subtracting the second equation from the first we find:

$x = \left(3 x + y\right) - \left(2 x + y\right) = 9 - 4 = 5$

Then substitute $x = 5$ in the second equation to get:

$4 = 2 \cdot 5 + y = 10 + y$

Subtract $10$ from both ends to get:

$y = 4 - 10 = - 6$