# How do you find the value of y that makes (3,y) a solution to the equation 3x-y=4?

Apr 9, 2015

If (3,y) is a solution to $3 x - y = 4$, we can substitute $x = 3$ in the equation.

We get

$\left(3 \cdot 3\right) - y = 4$

$9 - y = 4$

Transposing 9 to the right hand side, we get

$- y = 4 - 9$

$- y = - 5$

Multiplying both sides with $- 1$, we get

color(green)( y = 5