72=r(18)

Solution for 72=r(18) equation:

Simplifying
72 = r(18)

Reorder the terms for easier multiplication:
72 = 18r

Solving
72 = 18r

Solving for variable 'r'.

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

Add '-18r' to each side of the equation.
72 + -18r = 18r + -18r

Combine like terms: 18r + -18r = 0
72 + -18r = 0

Add '-72' to each side of the equation.
72 + -72 + -18r = 0 + -72

Combine like terms: 72 + -72 = 0
0 + -18r = 0 + -72
-18r = 0 + -72

Combine like terms: 0 + -72 = -72
-18r = -72

Divide each side by '-18'.
r = 4

Simplifying
r = 4