72=r*8

Solution for 72=r*8 equation:

Simplifying
72 = r * 8

Reorder the terms for easier multiplication:
72 = 8r

Solving
72 = 8r

Solving for variable 'r'.

Move all terms containing r to the left, all other terms to the right.

Add '-8r' to each side of the equation.
72 + -8r = 8r + -8r

Combine like terms: 8r + -8r = 0
72 + -8r = 0

Add '-72' to each side of the equation.
72 + -72 + -8r = 0 + -72

Combine like terms: 72 + -72 = 0
0 + -8r = 0 + -72
-8r = 0 + -72

Combine like terms: 0 + -72 = -72
-8r = -72

Divide each side by '-8'.
r = 9

Simplifying
r = 9