Time taken to swim 20 laps = 2.5 minutes
Hence, time taken to swim 1 lap will be = [tex]\frac{2.5}{20}[/tex] =0.125 minutes
Or convert it into seconds = [tex]0.125*60=7.5[/tex] seconds
Hence, Zoe's swim rate is 1 lap per 0.125 minutes. Or 1 lap per 7.5 seconds.