What has happened to the percentage of total national income going to the middle class between 1980 and 2012

Assume that a local bank sells two services, checking accounts and atm card services. the bank’s only two customers are mr. donethat and ms. beenthere. mr. donethat is willing to pay $8 a month for the bank to service his checking account and $2 a month for unlimited use of his atm card. ms. beenthere is willing to pay only $5 for a checking account, but is willing to pay $9 for unlimited use of her atm card. assume that the bank can provide each of these services at zero marginal cost.refer to scenario 17-5. if the bank is unable to use tying, what is the profit-maximizing price to charge for a checking account