Dude use your head to do the math. It's not that difficult....just break it down one at a time.

Odd of picking a 75 watter the first time are 6/15. Now with out replacement odds of picking it a second time are 5/14. On the third time you don't wanna pick it so it's 9/13. Multiply all three together.

Don't be a lil b*tch.