We know that in total there are 50 lawyers, and 25 of them are males, so the other 25 are females, and we know too that 5 of the 25 female lawyers are over 40 years old, so the probability that the lawyer is a female under the 40 years old: is:
The probability is 4/5 because we took the female group that is 25 and the lawyers that are under 40 years old is 20.