Calculate the slope from 2 points. Start with the first set. The first way is to solve for the equation of a line with one point and the equation of a line that runs perpendicular to it.
Substitute the slope for m in the slope intercept form of the equation.
To solve a literal equation. To solve two equations with two variables isolate one variable and plug its solution into the other equation. Do this and re-write your equation in the form. Add or Subtract the same value from both sides.