To add minutes and seconds, you need to convert the minutes to seconds, and then you can add them.
For example , to add 3 minutes and 100 seconds
1.- convert 3 minutes to seconds.
Since 1 minute is equal to 60 seconds, 3 minutes will be:
3 minutes are equal to 180 seconds.
2.- Add the result from 1, to the seconds:
3 minutes and 100 seconds, when we add then we get 280 seconds.