5 red, 3 yellow, and 2 blue....for a total of 10 marbles
P(first one being blue) = 2/10 which reduces to 1/5
not replaced
P(second one is blue) = 1/9...because u already pick a blue, meaning there is only 1 left, and there is one less marble, so there is a total of 9 marbles.
P(both events happening) = 1/5 * 1/9 = 1/45 <==