You will need to figure out the total amount of time she spent arranging baskets (20 mins x 5 baskets = 100 mins). You will then subtract this period of time from the beginning time. So we will go back 1 hour and 40 minutes from 4:10 p.m. This would put you starting the arrangements at 2:30 p.m. Go back to 3:10 pm for the hour and 40 minutes before that is 2:30 pm.