72=r(90)

Solution for 72=r(90) equation:

Simplifying
72 = r(90)

Reorder the terms for easier multiplication:
72 = 90r

Solving
72 = 90r

Solving for variable 'r'.

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

Add '-90r' to each side of the equation.
72 + -90r = 90r + -90r

Combine like terms: 90r + -90r = 0
72 + -90r = 0

Add '-72' to each side of the equation.
72 + -72 + -90r = 0 + -72

Combine like terms: 72 + -72 = 0
0 + -90r = 0 + -72
-90r = 0 + -72

Combine like terms: 0 + -72 = -72
-90r = -72

Divide each side by '-90'.
r = 0.8

Simplifying
r = 0.8