3(1[3y-8]1)=21

Solution for 3(1[3y-8]1)=21 equation:

Simplifying
3(1[3y + -8] * 1) = 21

Reorder the terms:
3(1[-8 + 3y] * 1) = 21

Reorder the terms for easier multiplication:
3(1 * 1[-8 + 3y]) = 21

Multiply 1 * 1
3(1[-8 + 3y]) = 21
3([-8 * 1 + 3y * 1]) = 21
3([-8 + 3y]) = 21
(-8 * 3 + 3y * 3) = 21
(-24 + 9y) = 21

Solving
-24 + 9y = 21

Solving for variable 'y'.

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

Add '24' to each side of the equation.
-24 + 24 + 9y = 21 + 24

Combine like terms: -24 + 24 = 0
0 + 9y = 21 + 24
9y = 21 + 24

Combine like terms: 21 + 24 = 45
9y = 45

Divide each side by '9'.
y = 5

Simplifying
y = 5