80=21w-w^2

Solution for 80=21w-w^2 equation:

Simplifying
80 = 21w + -1w2

Solving
80 = 21w + -1w2

Solving for variable 'w'.

Reorder the terms:
80 + -21w + w2 = 21w + -21w + -1w2 + w2

Combine like terms: 21w + -21w = 0
80 + -21w + w2 = 0 + -1w2 + w2
80 + -21w + w2 = -1w2 + w2

Combine like terms: -1w2 + w2 = 0
80 + -21w + w2 = 0

Factor a trinomial.
(5 + -1w)(16 + -1w) = 0

Subproblem 1
Set the factor '(5 + -1w)' equal to zero and attempt to solve:

Simplifying
5 + -1w = 0

Solving
5 + -1w = 0

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

Add '-5' to each side of the equation.
5 + -5 + -1w = 0 + -5

Combine like terms: 5 + -5 = 0
0 + -1w = 0 + -5
-1w = 0 + -5

Combine like terms: 0 + -5 = -5
-1w = -5

Divide each side by '-1'.
w = 5

Simplifying
w = 5
Subproblem 2
Set the factor '(16 + -1w)' equal to zero and attempt to solve:

Simplifying
16 + -1w = 0

Solving
16 + -1w = 0

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

Add '-16' to each side of the equation.
16 + -16 + -1w = 0 + -16

Combine like terms: 16 + -16 = 0
0 + -1w = 0 + -16
-1w = 0 + -16

Combine like terms: 0 + -16 = -16
-1w = -16

Divide each side by '-1'.
w = 16

Simplifying
w = 16
Solution
w = {5, 16}