To find how many more laps Tim and Amy need to do before they complete the same number of laps as Nick and Kate, we first need to find how many laps Tim and Amy did when Nick and Kate finished 52 laps.
Since we know that Nick and Kate can pedal 4 times faster we can represent that as:
Let 4x = 52 Nick and Kate
Let x = Tim and Amy Laps
4x = 52
x = 13
So when Nick and Kate finished the 52 laps, Tim and Amy already had 13 Laps.
So to find the number of laps left, we simply subtract the number of total laps done by Nick and Kate to the number of laps that Tim and Amy currently did.
Total Laps Left = 52 - 13
Total Laps Left = 39 Laps