Answer :
Out of the first box the possibility would be 3:12 or 3 out of 12. The second box would be 7:10 or 7 out of 10
3 pencils and 9 pens = 12 total
probability of picking pencil in 1st box is 3/12 which reduces to 1/4
7 pencils and 3 crayons = 10 total
probability of picking pencil from 2nd box is 7/10
probability of both = (1/4 * 7/10) = 7/40 <==
probability of picking pencil in 1st box is 3/12 which reduces to 1/4
7 pencils and 3 crayons = 10 total
probability of picking pencil from 2nd box is 7/10
probability of both = (1/4 * 7/10) = 7/40 <==