Subtracting clock times from other clock times (as Strings)?

Morning all,

I’ve seen the formatter used to add a value to an existing time, but I can’t seem to find any examples of just simply adding and subtracting two values that are “mm:ss”.

I’ve got them as strings–they came from a timer().

I can add, for example, 5 minutes (5*60) in the add interval method, but I can’t figure out how to pass an existing mm:ss into those parenthesis.

for example: 04:40 + 5:50. or, 11:00 - 10:15.