Math trick

I have this question posted by my professor... I hope I can understand it further via this forum.
Q: Think of a #
Multiply by five
Add eight
Subtract three
Divide by five
Subtract the # you first thought of.
a) show how the trick works
b) two steps in the trick can be combined into one without changing the end result, which are they?
c) what would the step replacing them be?

Thank you