Answer:
37.5 parcels in 5 minutes. Round down to 37, if required for the purpose of the calculation.
Explanation:
Let M and K be the rates Michael and Kate can pack parcels, in parcels/minute, or p/m.
M = (10/3)p/m
K = (7/2)p/m
When they work together for 5 minutes, we can calculate the numbers of parcels each pack.
Michael: ((10/3)p/m)*(5m) = 20 p
Kate: ((7/2)p/m)*(5m) = 17.5 p
Total = 37.5 parcels