Question

m = \frac{y_1 - y_2}{x_1 - x_2}, solve for y_1

Explanation:

Step1: Multiply both sides by denominator

$m(x_1 - x_2)=y_1 - y_2$

Step2: Isolate $y_1$

$y_1=m(x_1 - x_2)+y_2$

Answer:

$y_1=m(x_1 - x_2)+y_2$