Finding the probability of a random person

Of a group of patients having injuries, 28% visit both a physical therapist and a chiropractor and 8% visit neither. Say that the probability of visiting a physical therapist exceeds the probability of visiting a chiropractor by 16%. What is the probability of a randomly selected person from this group visiting a physical therapist?

When I solve the problem, I total up the percentages 28, 8, and 16. Therefore, I say the probability would be 16/52. But when I compare my answer to the back of the book they have 0.68 which makes no sense to me.