An hour was 60 minutes, now it is 100 minutes, but is still as long as before. So the length of 60 minutes before is the same length as 100 minutes now. It can be expressed as 60 x MB (MB stands for minutes before) = 100 x MA (MA stands for Minutes After).
60 x MB = 100 x MA.
Now since an MB (Minute Before) is 60 seconds long, one can replace MB with 60 seconds.
60 x (60 seconds) = 100 x MA
3600 seconds = 100 x MA
If one divides the equation by 100 we get
36 seconds = MA
Or
Minutes After = 36 seconds.
So if an hour is changed to be 100 minutes long but still as long as before, than a minute would have to be 36 seconds, unless if you would rather change the definition of a second instead.
