90=6(1+2r)

Solution for 90=6(1+2r) equation:

Simplifying
90 = 6(1 + 2r)
90 = (1 * 6 + 2r * 6)
90 = (6 + 12r)

Solving
90 = 6 + 12r

Solving for variable 'r'.

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

Add '-12r' to each side of the equation.
90 + -12r = 6 + 12r + -12r

Combine like terms: 12r + -12r = 0
90 + -12r = 6 + 0
90 + -12r = 6

Add '-90' to each side of the equation.
90 + -90 + -12r = 6 + -90

Combine like terms: 90 + -90 = 0
0 + -12r = 6 + -90
-12r = 6 + -90

Combine like terms: 6 + -90 = -84
-12r = -84

Divide each side by '-12'.
r = 7

Simplifying
r = 7