20=2(pi)r

Solution for 20=2(pi)r equation:

Simplifying
20 = 2(pi) * r

Multiply ip * r
20 = 2ipr

Solving
20 = 2ipr

Solving for variable 'i'.

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

Add '-2ipr' to each side of the equation.
20 + -2ipr = 2ipr + -2ipr

Combine like terms: 2ipr + -2ipr = 0
20 + -2ipr = 0

Add '-20' to each side of the equation.
20 + -20 + -2ipr = 0 + -20

Combine like terms: 20 + -20 = 0
0 + -2ipr = 0 + -20
-2ipr = 0 + -20

Combine like terms: 0 + -20 = -20
-2ipr = -20

Divide each side by '-2pr'.
i = 10p-1r-1

Simplifying
i = 10p-1r-1