90=.2(n)

Solution for 90=.2(n) equation:

Simplifying
90 = 0.2(n)

Solving
90 = 0.2n

Solving for variable 'n'.

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

Add '-0.2n' to each side of the equation.
90 + -0.2n = 0.2n + -0.2n

Combine like terms: 0.2n + -0.2n = 0.0
90 + -0.2n = 0.0

Add '-90' to each side of the equation.
90 + -90 + -0.2n = 0.0 + -90

Combine like terms: 90 + -90 = 0
0 + -0.2n = 0.0 + -90
-0.2n = 0.0 + -90

Combine like terms: 0.0 + -90 = -90
-0.2n = -90

Divide each side by '-0.2'.
n = 450

Simplifying
n = 450