b-7[b-6(1-b)]=138

Solution for b-7[b-6(1-b)]=138 equation:

Simplifying
b + -7[b + -6(1 + -1b)] = 138
b + -7[b + (1 * -6 + -1b * -6)] = 138
b + -7[b + (-6 + 6b)] = 138

Reorder the terms:
b + -7[-6 + b + 6b] = 138

Combine like terms: b + 6b = 7b
b + -7[-6 + 7b] = 138
b + [-6 * -7 + 7b * -7] = 138
b + [42 + -49b] = 138

Reorder the terms:
42 + b + -49b = 138

Combine like terms: b + -49b = -48b
42 + -48b = 138

Solving
42 + -48b = 138

Solving for variable 'b'.

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

Add '-42' to each side of the equation.
42 + -42 + -48b = 138 + -42

Combine like terms: 42 + -42 = 0
0 + -48b = 138 + -42
-48b = 138 + -42

Combine like terms: 138 + -42 = 96
-48b = 96

Divide each side by '-48'.
b = -2

Simplifying
b = -2