Here, we are to calculate the difference in the amount of time in which both of them spent working.
Mathematically, that would be the time spent by Inez minus the time spent by Joe
= 7 hrs 23 minutes - 4 hrs 51 minutes
This works like normal arithmetic subtraction;
Since we cannot subtract 51 minutes from 23 minutes, we need to borrow 1 hour ( 60 minutes) from 7 , and it becomes 6 while our minutes become (60 + 23 = 83 minutes).
So the difference here will be (6-4)hrs and (83-51) minutes = 2 hrs 32 minutes
