42=7(b-81)

Solution for 42=7(b-81) equation:

Simplifying
42 = 7(b + -81)

Reorder the terms:
42 = 7(-81 + b)
42 = (-81 * 7 + b * 7)
42 = (-567 + 7b)

Solving
42 = -567 + 7b

Solving for variable 'b'.

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

Add '-7b' to each side of the equation.
42 + -7b = -567 + 7b + -7b

Combine like terms: 7b + -7b = 0
42 + -7b = -567 + 0
42 + -7b = -567

Add '-42' to each side of the equation.
42 + -42 + -7b = -567 + -42

Combine like terms: 42 + -42 = 0
0 + -7b = -567 + -42
-7b = -567 + -42

Combine like terms: -567 + -42 = -609
-7b = -609

Divide each side by '-7'.
b = 87

Simplifying
b = 87