Me to solve this problem you very much

4 swimmers swam 100 meters each.
You know the total time all 4 swimmers took to complete the race.
You know the individual times for 3 of the 4 swimmers.
Add the three individual times, and subtract the sum from the total time.
That will give you the time of the 4th swimmer.

First, you need to add 52.58 sec + 59.19 sec + 50.73 sec.

52.58 sec + 59.19 sec + 50.73 sec = 162.5 sec

Now we convert this time into minutes and seconds.

60 seconds = 1 minute
120 seconds = 2 minutes
180 seconds = 3 minutes

The sum we have is 162.5 seconds, so it is between 2 and 3 minutes.

2 minutes = 120 sec, so subtract 120 sec from 162.5 sec.

162.5 seconds - 120 seconds = 42.5 seconds

The sum, 162.5 sec = 2 minutes 42.5 sec.

Now we have the sum we need, 2 minutes, 42.5 sec.
We need to subtract this sum from 3 minutes 29.35 seconds.

      3 min 29.35 sec
  -   2 min  42.5  sec


Since we can't subtract 42.5 from 29.35, we borrow 1 minute from the 3 minutes. 1 min = 60 sec, so we borrow 1 min from 3 min, and we add 60 sec to 29.35 sec.

      2 min 89.35 sec
  -   2 min  42.5  sec

      0 min  46.85 sec

The difference is 46.85 sec.

the 4th swimmer swam in 46.85 seconds.

What am i doing here. add?