What is the formula of slope?

the forula of slope is :

* Y2- Y / X2 - X

* the x2 , y2 means the second varible

example:

(4, 10) (-5, 7)

* 4= X 10=Y -5=X2 7=Y2

7-10 / -5 -4= 1/3

* y= mx + b

1/3x + b

1/3(-5) +b

-5/3 +b

26/3 = b or 8.6666..

*now plug in for forlmula

y= 1/3x + 8.6666... or y=1/3x + 26/3