Red, orange, yellow, green and blue balls

You have a bag with 1 red ball, 2 orange balls, 3 yellow balls, 4 green balls, and 5 blue balls.

You pick three out (without replacement) at random.

The probability each is a different color is $$\dfrac ab$$, where $$a$$ and $$b$$ are coprime positive integers.

What is $$a+b$$?

×