Given points are .

First, find the slope.

Substitute 29 for y₂,  20 for y₁, 12 for x₂, and 15 for x₁  in slope formula.

                         (Subtract: )

                              (Subtract: )

                          (Simplify)

                               (Cancel common terms)

You know the slope and a point on the line, so use point - slope form

with either given point to write an equation of line.

Choose .

            (Substitute 20 for y₁, 15 for x₁ and )   (Apply distributive property: )

            (Multiply: )

                 (Divide: )

Apply addition property of equality: If a = b then a + c = b + c.

(Add 20 to each side)

           (Apply additive inverse property: )

                 (Apply additive identity property: )

                       (Add: )

The equation of line is .