Lucy arrived at school very early today. She cleaned the classroom for 10 minutes and then she read for 15 minutes. It was 8:15 AM when she finished reading. What time did Lucy arrive at school?
First, let’s find the total elapsed time. It is 10 min + 15 min = 25 min.
The end time is 8:15 AM, so the starting time is 7:50 AM