123=3(5+6b)

Solution for 123=3(5+6b) equation:

Simplifying
123 = 3(5 + 6b)
123 = (5 * 3 + 6b * 3)
123 = (15 + 18b)

Solving
123 = 15 + 18b

Solving for variable 'b'.

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

Add '-18b' to each side of the equation.
123 + -18b = 15 + 18b + -18b

Combine like terms: 18b + -18b = 0
123 + -18b = 15 + 0
123 + -18b = 15

Add '-123' to each side of the equation.
123 + -123 + -18b = 15 + -123

Combine like terms: 123 + -123 = 0
0 + -18b = 15 + -123
-18b = 15 + -123

Combine like terms: 15 + -123 = -108
-18b = -108

Divide each side by '-18'.
b = 6

Simplifying
b = 6