The fountain contains 20 pennies and 9 dimes. a coin is randomly taken and not replaced. a second coin is randomly taken. what is the probability that both coins are pennies?

Well, the first coin has chance to be a penny. When it is a penny, the only valid case (the other case gives 0 for the multiplications later, so it is ignored) gives chance for the second one to be a penny. The result is , which is , or about 46.80% (rounded to the first 2 decimals)