First subtract 3 from both sides of the equal sign.
9s + 3 = 57
- 3 -3
9s = 54
Then divide both sides by 9.
9s = 54
/9 /9
s = 6
You can check it by plugging it back into the equation.
9s + 3 = 57
9 * 6 + 3= 57
54 + 3 = 37
57 = 57
Yep! It's correct! :)
Hope that helped. Algebra can be tricky sometimes I know but it's really just balancing equations.