probability of overweight OR female question

Hi, can anyone please help me with this question? I'm quite confused this moment.

In a certain population, containing an equal number of adult males and females, five percent are overweight. Twenty percent of the overweight are female. One person is selected at random from the population. What is the probability that the person is female OR overweight?

Should I try to calculate $\displaystyle P(Female \cup Overweight)$ ? If that's what I should aim for, how do I do it? I'm so confused.