Income of the student per month is $600 each month.
For month of September: the rental expenditure : $250, Buss pass is $40, book expenditures is $ 150, food expenditure is $50, clothes expenditure is $50 and discretionary spending is $50.
So after all the expenditure, the money you will be able to save is $10.
For the month of October : rental expenditure : $250, buss pass $40, clothes expenditure $50, food expenditure $50, discretionary expenditure $50.
So after all the expenditure, the saving at the end of October with you would be $170, allowing you to buy the ticket to visit home to your family which would cost $100.