You transform it to a multiplication by multiplying the first term (in this case 1/9) by the inverse of the second term (which is in this case 9/6, his inverse is 6/9) so we get then you divide each number by 3, So we get Hope this Helps :)
There are marbles in total. Out of those, are blue, so the probability of pulling a blue marble is . However, this is only the probability of pulling a blue marble when marble is pulled at random. Therefore, we can expect a blue marble to be pulled times if marble is pulled times at random. Hope this helps!