21(y-6)(y-20)=0

Solution for 21(y-6)(y-20)=0 equation:

Simplifying
21(y + -6)(y + -20) = 0

Reorder the terms:
21(-6 + y)(y + -20) = 0

Reorder the terms:
21(-6 + y)(-20 + y) = 0

Multiply (-6 + y) * (-20 + y)
21(-6(-20 + y) + y(-20 + y)) = 0
21((-20 * -6 + y * -6) + y(-20 + y)) = 0
21((120 + -6y) + y(-20 + y)) = 0
21(120 + -6y + (-20 * y + y * y)) = 0
21(120 + -6y + (-20y + y2)) = 0

Combine like terms: -6y + -20y = -26y
21(120 + -26y + y2) = 0
(120 * 21 + -26y * 21 + y2 * 21) = 0
(2520 + -546y + 21y2) = 0

Solving
2520 + -546y + 21y2 = 0

Solving for variable 'y'.

Factor out the Greatest Common Factor (GCF), '21'.
21(120 + -26y + y2) = 0

Factor a trinomial.
21((6 + -1y)(20 + -1y)) = 0

Ignore the factor 21.
Subproblem 1
Set the factor '(6 + -1y)' equal to zero and attempt to solve:

Simplifying
6 + -1y = 0

Solving
6 + -1y = 0

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

Add '-6' to each side of the equation.
6 + -6 + -1y = 0 + -6

Combine like terms: 6 + -6 = 0
0 + -1y = 0 + -6
-1y = 0 + -6

Combine like terms: 0 + -6 = -6
-1y = -6

Divide each side by '-1'.
y = 6

Simplifying
y = 6
Subproblem 2
Set the factor '(20 + -1y)' equal to zero and attempt to solve:

Simplifying
20 + -1y = 0

Solving
20 + -1y = 0

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

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

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

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

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

Simplifying
y = 20
Solution
y = {6, 20}