a large pile of coins consists of pennies, nickels, dimes, and quarters. use the method shown in example 9.6.2 to answer the following questions. (a) how many different collections of 40 coins can be chosen if there are at least 40 of each kind of coin? collections (b) if the pile contains only 20 quarters but at least 40 of each other kind of coin, how many collections of 40 coins can be chosen? collections (c) if the pile contains only 30 dimes but at least 40 of each other kind of coin, how many collections of 40 coins can be chosen? collections (d) if the pile contains only 20 quarters and only 30 dimes but at least 40 of each other kind of coin, how many collections of 40 coins can be chosen? collections