In a class of 100 people, 60 of them are math majors, and 75 of them are

Question:

In a class of 100 people, 60 of them are math majors, and 75 of them are physics majors. There are no students majoring in anything else in this class. This means that some of the students are double-majoring in both math and physics. A student is picked at random. What is the probability the student is double-majoring?