Consider a box containing 3 blue, 2 red, and 5 clear marbles.

When drawing 2 marbles without replacements, chances of drawing a blue then clear is?

The prob. Of drawing a blue is 3/10. See?

Since we are not replacing, there are 9 left, so the prob. Of drawing a clear is 5/9

(3/10)(5/9)=1/6