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Explanation:
3/13 = 15/65 after multiplying top and bottom by 5
2/5 = 26/65 after multiplying top and bottom by 13
Let's say there are 65 marbles in the bowl. That would mean 15 of them are red (since 15/65 reduces to 3/13) and 26 are blue. That gives 15+26 = 41 so far. Leaving 65-41 = 24 marbles that must be green.
The probability of selecting a green marble is 24/65. Once that first green marble is taken out, it is not replaced. We have 65-1 = 64 marbles left, 15 of which are red. The probability of picking red on the second selection is 15/64.
Multiply the fractions mentioned:
(24/65)*(15/64)
(24*15)/(65*64)
360/4160
9/104
