Knife and Fork operates as a restaurant. Its customers can pay by cash, debit, or credit card. For each debit transaction, John pays $0.30. For credit cards, John pays 4% of the total credit card transactions as processing fees. What percentage of the total revenue does Knife and Fork lose to transaction fees if 60% of its customers pay by credit card and 40% pay by debit?
a) 1.6%
b) 2.4%
c) 3.6%
d) 4.8%