The total number of coins needs to be 6*(number of quarters) = 6*15 = 90.

The number of coins now in the bag is 20+25+15 = 60.

The assumption is that the probability of drawing a particular coin does not depend on its value. If the drawing is done by any living entity or machine capable of distinguishing the coins by "feel", it seems unlikely to me that the probabilities could ever be equalized. Thus, the question has no meaning in the real world.

The number of coins now in the bag is 20+25+15 = 60.

**30 dimes must be added**.The assumption is that the probability of drawing a particular coin does not depend on its value. If the drawing is done by any living entity or machine capable of distinguishing the coins by "feel", it seems unlikely to me that the probabilities could ever be equalized. Thus, the question has no meaning in the real world.