Bits and Pieces bpp question number 133 2016/2017

Dear Tutor, another question is that if the company is considering opening on Sunday why 6o days are considered not 7 days? Question a says consider sunday incremental revenue exceeds incremental costs over a yearof period ?why here over a year of period is considered 6 days per week not seven days? I understand that Sunday revenue should be taken for calculation not including Sunday itself but the company opens for seven days not 6 days therefore I am confused

The question says that the average gross profit is 70%. It then says that on a Sunday it will be 20 % points lower. So on a Sunday it will only be 50%. The answer is showing all 7 days, but because the profit is different on Sundays it is having to calculate Sunday results (50 days a year) and other days results (300 days a year) separately.