First we have to add 12+16 so we can find how many marbles are left
12+16=38
Then, we subtract it from the total number of marbles.the outcome of this operation would be equivalent to the number of blue marbles
40-38=12
There are 12 blue marbles.
Now, the we have to use experimental probability if you are familiar with the term is that the number of outcomes(the blue marbles) must be over the total sample space(total marbles) in a fraction.
