Use slope formula to find the missing coordinate. (r, 1) and (5, -7) slope = 8/3

r=8

Step-by-step explanation:

The formula for slope is

m = (y2-y1)/ (x2-x1)

Substitute in what we know.

8/3 = (-7-1)/(5-r)

Simplify

8/3 = -8/(5-r)

We can use cross products to help us solve.

8 * (5-r) = 3 * (-8)

divide each side by 8

8/8 * (5-r) = 3 * (-8)/8

5-r = -3

Subtract 5 from each side

5-r-5 = -3-5

-r = -8

Multiply by -1

r = 8

c

step-by-step explanation: