3(1+6b)+3(6-3b)=21

Solution for 3(1+6b)+3(6-3b)=21 equation:

Simplifying
3(1 + 6b) + 3(6 + -3b) = 21
(1 * 3 + 6b * 3) + 3(6 + -3b) = 21
(3 + 18b) + 3(6 + -3b) = 21
3 + 18b + (6 * 3 + -3b * 3) = 21
3 + 18b + (18 + -9b) = 21

Reorder the terms:
3 + 18 + 18b + -9b = 21

Combine like terms: 3 + 18 = 21
21 + 18b + -9b = 21

Combine like terms: 18b + -9b = 9b
21 + 9b = 21

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

Combine like terms: 21 + -21 = 0
0 + 9b = 21 + -21
9b = 21 + -21

Combine like terms: 21 + -21 = 0
9b = 0

Solving
9b = 0

Solving for variable 'b'.

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

Divide each side by '9'.
b = 0

Simplifying
b = 0