90=p(.05)(4)

Solution for 90=p(.05)(4) equation:

Simplifying
90 = p(0.05)(4)

Reorder the terms for easier multiplication:
90 = 0.05 * 4p

Multiply 0.05 * 4
90 = 0.2p

Solving
90 = 0.2p

Solving for variable 'p'.

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

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

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

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

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

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

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

Simplifying
p = 450