Given points are .

First, find the slope.

Substitute 4 for y₂,  2 for y₁, 3 for x₂, and 1 for x₁  in slope formula.

                            (Product of two same signs is positive)

                            (Add: )

                                  (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 2 for y₁, 1 for x₁ and )

                 (Product of two same signs is positive)

             (Apply distributive property: )

                   (Multiply: )

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

       (Add to 2 each side)

             (Apply additive inverse property: )

                  (Apply additive identity property: )

                        (Add: )

The equation of line is .