-3=-4(-7y+1)*5(8+2y)

Solution for -3=-4(-7y+1)*5(8+2y) equation:

Simplifying
-3 = -4(-7y + 1) * 5(8 + 2y)

Reorder the terms:
-3 = -4(1 + -7y) * 5(8 + 2y)

Reorder the terms for easier multiplication:
-3 = -4 * 5(1 + -7y)(8 + 2y)

Multiply -4 * 5
-3 = -20(1 + -7y)(8 + 2y)

Multiply (1 + -7y) * (8 + 2y)
-3 = -20(1(8 + 2y) + -7y * (8 + 2y))
-3 = -20((8 * 1 + 2y * 1) + -7y * (8 + 2y))
-3 = -20((8 + 2y) + -7y * (8 + 2y))
-3 = -20(8 + 2y + (8 * -7y + 2y * -7y))
-3 = -20(8 + 2y + (-56y + -14y2))

Combine like terms: 2y + -56y = -54y
-3 = -20(8 + -54y + -14y2)
-3 = (8 * -20 + -54y * -20 + -14y2 * -20)
-3 = (-160 + 1080y + 280y2)

Solving
-3 = -160 + 1080y + 280y2

Solving for variable 'y'.

Combine like terms: -3 + 160 = 157
157 + -1080y + -280y2 = -160 + 1080y + 280y2 + 160 + -1080y + -280y2

Reorder the terms:
157 + -1080y + -280y2 = -160 + 160 + 1080y + -1080y + 280y2 + -280y2

Combine like terms: -160 + 160 = 0
157 + -1080y + -280y2 = 0 + 1080y + -1080y + 280y2 + -280y2
157 + -1080y + -280y2 = 1080y + -1080y + 280y2 + -280y2

Combine like terms: 1080y + -1080y = 0
157 + -1080y + -280y2 = 0 + 280y2 + -280y2
157 + -1080y + -280y2 = 280y2 + -280y2

Combine like terms: 280y2 + -280y2 = 0
157 + -1080y + -280y2 = 0

Begin completing the square.  Divide all terms by
-280 the coefficient of the squared term: 

Divide each side by '-280'.
-0.5607142857 + 3.857142857y + y2 = 0

Move the constant term to the right:

Add '0.5607142857' to each side of the equation.
-0.5607142857 + 3.857142857y + 0.5607142857 + y2 = 0 + 0.5607142857

Reorder the terms:
-0.5607142857 + 0.5607142857 + 3.857142857y + y2 = 0 + 0.5607142857

Combine like terms: -0.5607142857 + 0.5607142857 = 0.0000000000
0.0000000000 + 3.857142857y + y2 = 0 + 0.5607142857
3.857142857y + y2 = 0 + 0.5607142857

Combine like terms: 0 + 0.5607142857 = 0.5607142857
3.857142857y + y2 = 0.5607142857

The y term is 3.857142857y.  Take half its coefficient (1.928571429).
Square it (3.719387757) and add it to both sides.

Add '3.719387757' to each side of the equation.
3.857142857y + 3.719387757 + y2 = 0.5607142857 + 3.719387757

Reorder the terms:
3.719387757 + 3.857142857y + y2 = 0.5607142857 + 3.719387757

Combine like terms: 0.5607142857 + 3.719387757 = 4.2801020427
3.719387757 + 3.857142857y + y2 = 4.2801020427

Factor a perfect square on the left side:
(y + 1.928571429)(y + 1.928571429) = 4.2801020427

Calculate the square root of the right side: 2.068840749

Break this problem into two subproblems by setting 
(y + 1.928571429) equal to 2.068840749 and -2.068840749.

Subproblem 1
y + 1.928571429 = 2.068840749

Simplifying
y + 1.928571429 = 2.068840749

Reorder the terms:
1.928571429 + y = 2.068840749

Solving
1.928571429 + y = 2.068840749

Solving for variable 'y'.

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

Add '-1.928571429' to each side of the equation.
1.928571429 + -1.928571429 + y = 2.068840749 + -1.928571429

Combine like terms: 1.928571429 + -1.928571429 = 0.000000000
0.000000000 + y = 2.068840749 + -1.928571429
y = 2.068840749 + -1.928571429

Combine like terms: 2.068840749 + -1.928571429 = 0.14026932
y = 0.14026932

Simplifying
y = 0.14026932

Subproblem 2
y + 1.928571429 = -2.068840749

Simplifying
y + 1.928571429 = -2.068840749

Reorder the terms:
1.928571429 + y = -2.068840749

Solving
1.928571429 + y = -2.068840749

Solving for variable 'y'.

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

Add '-1.928571429' to each side of the equation.
1.928571429 + -1.928571429 + y = -2.068840749 + -1.928571429

Combine like terms: 1.928571429 + -1.928571429 = 0.000000000
0.000000000 + y = -2.068840749 + -1.928571429
y = -2.068840749 + -1.928571429

Combine like terms: -2.068840749 + -1.928571429 = -3.997412178
y = -3.997412178

Simplifying
y = -3.997412178

Solution
The solution to the problem is based on the solutions
from the subproblems.
y = {0.14026932, -3.997412178}