I'm trying to figure minutes that children are in an after school program to do billing. The teachers clock them in anytime between 3:15pm and 3:45pm but I want to start billing at 3:30

Data is formatted this way incoming: 

```
Child 1:  3:27:00 PM   4:39:00 PM
Child 2:  3:34:00 PM   5:21:00 PM
Child 3:  3:37:00 PM   4:45:00 PM

```

So I'd want to update all those in times to 3:30:00 PM so I can figure the hours/minutes that they were in after care to charge them .10/minute. Can I do that in all one formula or do I need to break it down into a few different steps?

Any help is super appreciated! Thanks in advance! :-)