Micro Economics Question, Please HELP!

Assume that a local bank sells two services, checking accounts and ATM card services.Mr. Don is willing to pay $8 a month for the bank to service his checking account and $10 a month for unlimited use of his ATM card. Ms. Ben is willing to pay only $5 for a checking account, but is willing to pay $15 for unlimited use of her ATM card. To keep this example simple, assume that the bank can provide each of these services at zero marginal cost.

A. if the bank is unable to use tying, what is the profit-maximizing price to charge for a checking account?

B. If the bank is unable to use tying, what is the profit-maximizing price to charge for unlimited use of an ATM card?

C. If the bank is able to use tying to price checking account and ATM service, what is the profit-maximizing price to charge for the "tied" good?

D. How much additional profit does the bank make when it switches to use of a tying strategy to price checking account and ATM service?

E. How much total surplus is generated from using tying to price the checking account and ATM service? How does that compare to the non tied pricing strategy? Which strategy has the largest dead weight loss?

Please show work I need help understanding these questions, Im really confused. Thanks!