HELP!

Suppose that there is a new test to determine whether people are carrying an active flu virus and can infect others, even though they are not experiencing any symptoms. If the false-positive rate for this test is .1, and the false-negative rate is .2, and 5% of the population being tested is carrying an active flu virus at any given time, what is the (approximate) probability that someone who tests positive is really carrying the flu virus?