Answer:
Let us assume that the number yellow balls are x, so the number of green balls are 12-x.
The probability that both marbles will be yellow is
(x/12) X (x-1)/11 = 5/33
(x(x-1))/132 = 5/33
(x(x-1))/4 = 5
(x(x-1)) = 5X4
(x(x-1)) = 20
we then get 12-5 , x=5
So we can conclude that thew number of yellow marbles is 5 and the number of green marbles is 7.
