-80=-5(-4b)

Solution for -80=-5(-4b) equation:

Simplifying
-80 = -5(-4b)

Remove parenthesis around (-4b)
-80 = -5 * -4b

Multiply -5 * -4
-80 = 20b

Solving
-80 = 20b

Solving for variable 'b'.

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

Add '-20b' to each side of the equation.
-80 + -20b = 20b + -20b

Combine like terms: 20b + -20b = 0
-80 + -20b = 0

Add '80' to each side of the equation.
-80 + 80 + -20b = 0 + 80

Combine like terms: -80 + 80 = 0
0 + -20b = 0 + 80
-20b = 0 + 80

Combine like terms: 0 + 80 = 80
-20b = 80

Divide each side by '-20'.
b = -4

Simplifying
b = -4