Probability of Selecting Same Color Balls

A box contains 15 balls: 7 red balls, 5 blue balls, and 3 green balls. If two balls are randomly selected from the box without replacement, what is the probability that both balls are of the same color?

To determine the probability, first calculate the total number of ways to select 2 balls from the 15 balls, and then find the number of favorable outcomes for each color.