Drawing from an UrnDiscrete Mathematics Level 5
In an urn, there are several colored balls, with equal numbers of each color. We add 14 balls which are all of the same new color, that is different from those in the urn. It is calculated that the probability of drawing, without replacement, two balls of the same color before the 14 balls are added, is equal to the probability of drawing, without replacement, two balls of the same color after the 14 balls are added. How many balls are there in the urn initially?