8b+21=15b

Solution for 8b+21=15b equation:

Simplifying
8b + 21 = 15b

Reorder the terms:
21 + 8b = 15b

Solving
21 + 8b = 15b

Solving for variable 'b'.

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

Add '-15b' to each side of the equation.
21 + 8b + -15b = 15b + -15b

Combine like terms: 8b + -15b = -7b
21 + -7b = 15b + -15b

Combine like terms: 15b + -15b = 0
21 + -7b = 0

Add '-21' to each side of the equation.
21 + -21 + -7b = 0 + -21

Combine like terms: 21 + -21 = 0
0 + -7b = 0 + -21
-7b = 0 + -21

Combine like terms: 0 + -21 = -21
-7b = -21

Divide each side by '-7'.
b = 3

Simplifying
b = 3