Of the last 41 customers at the student bookstore, 15 paid in cash, 16 used debit card ...

Of the last 41 customers at the student bookstore, 15 paid in cash, 16 used debit card, 20 used financial aid vouchers, 4 used cash and debit cards, 8 used a financial aid voucher and a debit card, 8 used cash and financial aid voucher, and 1 used all three. (a) How many used none of these payment types (b) How many used only a debit
(c) How many used cash and a financial aid voucher but not a debit card