When I calculate revised profit, is it right way to using revenue-expense formula? Then why prepayment is included in this calculation?

Question 20 John calculated that his profit for the year was $65,285. He then found that he had omitted a prepayment of $189. R T89 = C.AT. XV When he corrects the error, what is his revised profit for the year? C R-X A $64,907 B $65,096 $65,474 D $65,663