Hey, I have the following question... I know the probabilities for each event happening independently, but not in the way the question is asking. Should I multiply or add the probabilities? What should I do? Cheers!

The problem says that person A tosses a fair coin until it lands heads, and that then person B does the same. In the end, they toss it 10 times. What is the probability that person A only tossed it once?

Well, I have that the probability that person A gets heads with only once throw is 0.5, and that the probability that person gets heads with 9 throws is 9/(2^9)=9/512=0.02

So I don't know if I should add them (which would give P=0.52) or multiply them... or something different. Thanks a lot!