Answer
$y=-2$
Work Step by Step
The slope of the line through the two points $(x_{1},y_{1})$ and $(x_{2},y_{2})$ is given with the formula:
$m=\frac{y_{2}-y_{1}}{x_{2}-x_{1}}$
Now, we have to slove for y.
$-3=\frac{4-y}{1-3}$
$-3=\frac{4-y}{-2}$
Then, multiply with -2.
$6=4-y$
$6-4=-y$
$-y=2$
$y=-2$
