Question

Find the slope between the two points: (9,9) and (12,15)

Answer 1

Slope = Change in y / Change in x

Between (9, 9) and (12, 15).

We would use the coordinates from the second point minus that from the first point.

1st point = (9, 9),  2nd point = (12, 15)

Slope =  (15 - 9) / (12 - 9) 

         =  6 / 3

         =  2 

Slope = 2

Answer 2

The slope formula is $\frac{Y2-Y1}{X2-X1}$. For the two points, $(x,y)$. You can pick any of the Y and X from these two points, but only once. $\frac{9-15}{9-12}$ = $\frac{-6}{-3}$ = 2 or $\frac{15-9}{12-9}$ = $\frac{6}{3}$ = 2 and both will equal to. The answer for the slope is 2.