20=b(b-8)

Solution for 20=b(b-8) equation:

Simplifying
20 = b(b + -8)

Reorder the terms:
20 = b(-8 + b)
20 = (-8 * b + b * b)
20 = (-8b + b2)

Solving
20 = -8b + b2

Solving for variable 'b'.

Reorder the terms:
20 + 8b + -1b2 = -8b + 8b + b2 + -1b2

Combine like terms: -8b + 8b = 0
20 + 8b + -1b2 = 0 + b2 + -1b2
20 + 8b + -1b2 = b2 + -1b2

Combine like terms: b2 + -1b2 = 0
20 + 8b + -1b2 = 0

Factor a trinomial.
(10 + -1b)(2 + b) = 0

Subproblem 1
Set the factor '(10 + -1b)' equal to zero and attempt to solve:

Simplifying
10 + -1b = 0

Solving
10 + -1b = 0

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

Add '-10' to each side of the equation.
10 + -10 + -1b = 0 + -10

Combine like terms: 10 + -10 = 0
0 + -1b = 0 + -10
-1b = 0 + -10

Combine like terms: 0 + -10 = -10
-1b = -10

Divide each side by '-1'.
b = 10

Simplifying
b = 10
Subproblem 2
Set the factor '(2 + b)' equal to zero and attempt to solve:

Simplifying
2 + b = 0

Solving
2 + b = 0

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

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

Combine like terms: 2 + -2 = 0
0 + b = 0 + -2
b = 0 + -2

Combine like terms: 0 + -2 = -2
b = -2

Simplifying
b = -2
Solution
b = {10, -2}