When A student found the slope of a line that passes through -3 10 and 5 -7 to be 3 over 8 what mistake did he make?

He has to

1) subtract MINUS 7 for y'

2) Use MINUS 3 and MINUS 5 for x and x'

He incorrectly wrote this

(y - y') / (x - x')

like this:

(10 - 7) / 3 + 5)

He should have written this:

(10 - (-7)) / (-3 -5)

This comes out to

(10 + 7) / (- 3 -5)

17 / - 8

Correct answer:

Slope = 17 / - 8