Hey there. Is that all the question says? If so you could change it into one type of unit. Change it into just inches.
5 ft x (12 in / 1 ft) = 60 in
Then add the additional 3
60 in + 3 in = 63 inches. This value would then have 2 significant figures.
Hope that helps. Please let us know if you have any other questions about this problem. Good luck studying.