x(x+15)+(4x-20)=0

Solution for x(x+15)+(4x-20)=0 equation:

Simplifying
x(x + 15) + (4x + -20) = 0

Reorder the terms:
x(15 + x) + (4x + -20) = 0
(15 * x + x * x) + (4x + -20) = 0
(15x + x2) + (4x + -20) = 0

Reorder the terms:
15x + x2 + (-20 + 4x) = 0

Remove parenthesis around (-20 + 4x)
15x + x2 + -20 + 4x = 0

Reorder the terms:
-20 + 15x + 4x + x2 = 0

Combine like terms: 15x + 4x = 19x
-20 + 19x + x2 = 0

Solving
-20 + 19x + x2 = 0

Solving for variable 'x'.

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

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

Simplifying
-20 + -1x = 0

Solving
-20 + -1x = 0

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

Add '20' to each side of the equation.
-20 + 20 + -1x = 0 + 20

Combine like terms: -20 + 20 = 0
0 + -1x = 0 + 20
-1x = 0 + 20

Combine like terms: 0 + 20 = 20
-1x = 20

Divide each side by '-1'.
x = -20

Simplifying
x = -20
Subproblem 2
Set the factor '(1 + -1x)' equal to zero and attempt to solve:

Simplifying
1 + -1x = 0

Solving
1 + -1x = 0

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

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

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

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

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

Simplifying
x = 1
Solution
x = {-20, 1}