question:

We have 10 marbles in a bag: 5 red, 3 blue, 2 yellow. We randomly pull two marbleswithoutreplacement. If we pull two yellow marbles, we receive $20. If we pull two blue marbles, we receive $10. If we pull two red marbles, we receive $5. If we pull two marbles of different colors, we pay $4. Find the expected value of this game.

I won't try to explain how but I came up with: -8/15

Anyone else?