What is the answer to this algebra problem

First find the slope of the two coordinates.

Slope is represented by the equation:

M = y2 - y1 / x2 - x1

Substitute in the coordinates.

M = 9 - 8 / -15 - (-10)

M = 9 - 8 / -15 + 10

M = 1 / -5

M = - 1/5

Then use the equation a line:

y - y1 = m(x - x1)

y - 8 = -1/5(x - (-10)

y - 8 = -1/5(x + 10)

y - 8 = -1/5x - 2

y = -1/5x + 6 is the solution

The problem said : -10,8 =-2 and -15,9=-6