Given points are .

First, find the slope.

.

Substitute 9 for y₂,  3 for y₁, 2 for x₂, and 1 for x₁  in slope formula.

                   (Product of two same signs is positive)

                   (Add: )

                         (Subtract: )

                           (Divide: )

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 9 for y₁, 2 for x₁ and )   

         (Apply distributive property: )

               (Multiply: )

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

    (Add 9 to each side)

         (Apply additive inverse property: )

               (Apply additive identity property: )

                    (Add: )

The equation of line is .