We are given two peoples and their distance which they swam, and we need to find who swam farther, so let's start by coverting either sean's distance in km or Callie's distance in metres, also, maybe you need both, so I will do from both
i) As we know, 1km = 1000m
So, Callie swam (62/100)×1000 = 620 metres, also Sean swam 475 m, so as 620 m > 475 m, so Callie swam farther
ii) As we know, 1m = (1/1000) km
So, Sean swam (1/1000)×475 = 0.475 km, also Callie swam 0.62 km, so as 0.62 km > 0.475 km, so Callie swam farther
We are done!