Step 1: Note down the given points (or Identify two points on the line.)

Step 2: Select one to be (x_1, y_1) and the other to be (x_2, y_2).

Step  3:Use the slope equation to calculate slope.

            NOTE: Substitute given points in the formula.

          FORMULA: \frac{y_2 - y_1}{x_2 - x_1}

          EXAMPLE: Let's take the points (15, 8), (10, 7).

                             \frac{7 - 8}{15 - 10}