21=7b

Solution for 21=7b equation:

Simplifying
21 = 7b

Solving
21 = 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.
21 + -7b = 7b + -7b

Combine like terms: 7b + -7b = 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