After having a sonogram a pregnant woman learns that she will have twins, find the probability of identical twins given that the twins consist of two boys

What you need to do is the following:

Calculate the total number of identical twins which will be 2+2 = 4. and then total of twins is 12. The probability for her to have identical twins will be known with the following formula:

Identical twins = 4 / 12

that is 0.3333

The probability is 0.3333