-300=-20(-5b)

Solution for -300=-20(-5b) equation:

Simplifying
-300 = -20(-5b)

Remove parenthesis around (-5b)
-300 = -20 * -5b

Multiply -20 * -5
-300 = 100b

Solving
-300 = 100b

Solving for variable 'b'.

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

Add '-100b' to each side of the equation.
-300 + -100b = 100b + -100b

Combine like terms: 100b + -100b = 0
-300 + -100b = 0

Add '300' to each side of the equation.
-300 + 300 + -100b = 0 + 300

Combine like terms: -300 + 300 = 0
0 + -100b = 0 + 300
-100b = 0 + 300

Combine like terms: 0 + 300 = 300
-100b = 300

Divide each side by '-100'.
b = -3

Simplifying
b = -3