Answer
he can withdraw the money around 7 weeks which means he withdraw $280 and in his bank account he will have $220.
To find f(x) - g(x), simply subtract g(x) from f(x).

If you need to simplify, we can find a common denominator:
These could be be some of the answers to the problem. 6:3, 12:6, and 36:18
I do believe that the LCD of those would be 3