A clothing supplier sells T-shirts to retailers for $7 each. If a store agrees to buy more than 30, the supplier is willing to reduce the unit price by 3 cents for each shirt bought above 30, with a maximum single order of 100 shirts.
(a) How much does an order of 40 shirts cost?
(b) If the total cost of an order is $504.25, how many T-shirts did the store buy altogether?