What is a probability that a randomly selected student owns both a car and a cell phone

This is the question:

Suppose we are considering students are the University of Minnesota. Suppose 85% of all students own a cell phone, 40% own a car, and 5% own neither a car or a cell phone. What is the probability that a randomly selected student owns both a car and cell phone?

For any two events A and B

P(A or B) = P(A) + P(B) - P(AB)

So

P(cell phone or car) = P(cell phone) + P(car) - P(cell phone AND car)

You're given P(cell phone).
You're given P(car)
You're told that 5% own neither, so 95% own at least one. That means P(cell phone or car) = 95%.
Plug it all in and solve for the unknown.