You have to subtract both lap times, but before doing so you need to know what 2/5 is in decimal form. To do so, you must do 2 divided by 5, getting 0.4 seconds as it's a fraction converting to decimal. This means Fam swam 29.4 seconds, which instead of 2/5, you have 0.4 as your converted answer, so you would substitute it after 29. Then, you would do 29.40 subtracted by 28.7 and get 0.7 seconds as your answer to find out the difference of their swim times.
