Which steps are needed to solve this equation?
b+6=21

Subtract 6 from both sides of the equation.
The answer is b= 15.
Check the solution by substituting 15 for b.
Subtract 6 from the left side and add 6 to the right side of the equation
The answer is b-27
Check the solution by substituting 27 for b.
Add 6 to both sides of the equation.
The answer is b= 27
Check the solution by substituting 27 for b.
Add 6 to the left side and subtract 6 from the right side of the equation,
The answer is b= 15
Check the solution by substituting 15 for b.