we need to know how many weeks there are is a year , we know a year is 365 days and a week is 7 days so we do this to get the number of weeks 365÷7=52 weeks and 1 day , then we do 52÷6 to know the number of times she will pay : she will pay 8 times in a year for a total of 8x156=1248$ and she will also have an additional 4 weeks and one day with nothing to do (she cannot pay one more time as she still did not finish her 9th period)