The bell rings for school at 8:30 a.m. Elia must be there 15 minute before the bell. The trip to school takes 35 min. When should Elisa leave for school.

Answer 1

You could simply count on your fingers -- or you can subtract from the equivalent of 8:30.

7:90 - 50 = ?

Answer 2

8:30-15=8:15
8:15-35=7:40

7:40