320=-20x^2+320x-780

Solution for 320=-20x^2+320x-780 equation:

Simplifying
320 = -20x2 + 320x + -780

Reorder the terms:
320 = -780 + 320x + -20x2

Solving
320 = -780 + 320x + -20x2

Solving for variable 'x'.

Combine like terms: 320 + 780 = 1100
1100 + -320x + 20x2 = -780 + 320x + -20x2 + 780 + -320x + 20x2

Reorder the terms:
1100 + -320x + 20x2 = -780 + 780 + 320x + -320x + -20x2 + 20x2

Combine like terms: -780 + 780 = 0
1100 + -320x + 20x2 = 0 + 320x + -320x + -20x2 + 20x2
1100 + -320x + 20x2 = 320x + -320x + -20x2 + 20x2

Combine like terms: 320x + -320x = 0
1100 + -320x + 20x2 = 0 + -20x2 + 20x2
1100 + -320x + 20x2 = -20x2 + 20x2

Combine like terms: -20x2 + 20x2 = 0
1100 + -320x + 20x2 = 0

Factor out the Greatest Common Factor (GCF), '20'.
20(55 + -16x + x2) = 0

Factor a trinomial.
20((5 + -1x)(11 + -1x)) = 0

Ignore the factor 20.
Subproblem 1
Set the factor '(5 + -1x)' equal to zero and attempt to solve:

Simplifying
5 + -1x = 0

Solving
5 + -1x = 0

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

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

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

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

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

Simplifying
x = 5
Subproblem 2
Set the factor '(11 + -1x)' equal to zero and attempt to solve:

Simplifying
11 + -1x = 0

Solving
11 + -1x = 0

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

Add '-11' to each side of the equation.
11 + -11 + -1x = 0 + -11

Combine like terms: 11 + -11 = 0
0 + -1x = 0 + -11
-1x = 0 + -11

Combine like terms: 0 + -11 = -11
-1x = -11

Divide each side by '-1'.
x = 11

Simplifying
x = 11
Solution
x = {5, 11}