-3(3x+15)(-10+x)=35

Solution for -3(3x+15)(-10+x)=35 equation:

Simplifying
-3(3x + 15)(-10 + x) = 35

Reorder the terms:
-3(15 + 3x)(-10 + x) = 35

Multiply (15 + 3x) * (-10 + x)
-3(15(-10 + x) + 3x * (-10 + x)) = 35
-3((-10 * 15 + x * 15) + 3x * (-10 + x)) = 35
-3((-150 + 15x) + 3x * (-10 + x)) = 35
-3(-150 + 15x + (-10 * 3x + x * 3x)) = 35
-3(-150 + 15x + (-30x + 3x2)) = 35

Combine like terms: 15x + -30x = -15x
-3(-150 + -15x + 3x2) = 35
(-150 * -3 + -15x * -3 + 3x2 * -3) = 35
(450 + 45x + -9x2) = 35

Solving
450 + 45x + -9x2 = 35

Solving for variable 'x'.

Reorder the terms:
450 + -35 + 45x + -9x2 = 35 + -35

Combine like terms: 450 + -35 = 415
415 + 45x + -9x2 = 35 + -35

Combine like terms: 35 + -35 = 0
415 + 45x + -9x2 = 0

Begin completing the square.  Divide all terms by
-9 the coefficient of the squared term: 

Divide each side by '-9'.
-46.11111111 + -5x + x2 = 0

Move the constant term to the right:

Add '46.11111111' to each side of the equation.
-46.11111111 + -5x + 46.11111111 + x2 = 0 + 46.11111111

Reorder the terms:
-46.11111111 + 46.11111111 + -5x + x2 = 0 + 46.11111111

Combine like terms: -46.11111111 + 46.11111111 = 0.00000000
0.00000000 + -5x + x2 = 0 + 46.11111111
-5x + x2 = 0 + 46.11111111

Combine like terms: 0 + 46.11111111 = 46.11111111
-5x + x2 = 46.11111111

The x term is -5x.  Take half its coefficient (-2.5).
Square it (6.25) and add it to both sides.

Add '6.25' to each side of the equation.
-5x + 6.25 + x2 = 46.11111111 + 6.25

Reorder the terms:
6.25 + -5x + x2 = 46.11111111 + 6.25

Combine like terms: 46.11111111 + 6.25 = 52.36111111
6.25 + -5x + x2 = 52.36111111

Factor a perfect square on the left side:
(x + -2.5)(x + -2.5) = 52.36111111

Calculate the square root of the right side: 7.236097782

Break this problem into two subproblems by setting 
(x + -2.5) equal to 7.236097782 and -7.236097782.

Subproblem 1
x + -2.5 = 7.236097782

Simplifying
x + -2.5 = 7.236097782

Reorder the terms:
-2.5 + x = 7.236097782

Solving
-2.5 + x = 7.236097782

Solving for variable 'x'.

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

Add '2.5' to each side of the equation.
-2.5 + 2.5 + x = 7.236097782 + 2.5

Combine like terms: -2.5 + 2.5 = 0.0
0.0 + x = 7.236097782 + 2.5
x = 7.236097782 + 2.5

Combine like terms: 7.236097782 + 2.5 = 9.736097782
x = 9.736097782

Simplifying
x = 9.736097782

Subproblem 2
x + -2.5 = -7.236097782

Simplifying
x + -2.5 = -7.236097782

Reorder the terms:
-2.5 + x = -7.236097782

Solving
-2.5 + x = -7.236097782

Solving for variable 'x'.

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

Add '2.5' to each side of the equation.
-2.5 + 2.5 + x = -7.236097782 + 2.5

Combine like terms: -2.5 + 2.5 = 0.0
0.0 + x = -7.236097782 + 2.5
x = -7.236097782 + 2.5

Combine like terms: -7.236097782 + 2.5 = -4.736097782
x = -4.736097782

Simplifying
x = -4.736097782

Solution
The solution to the problem is based on the solutions
from the subproblems.
x = {9.736097782, -4.736097782}