Write an equation and solve:

1. a stock inventory of an item was 65 on monday morning. at the close of business on friday, the inventory level was 18. how many were sold during the week?

2. a person ran at 880 ft./min for the first 10 minutes of the 3 mile race before slowing their pace to finish the race with a total time of 20 minutes. what was their pace (in feet per minute) for the second part of the race.

3. jeffrey biked to the store at 12 mi./hr. but took his time on the way home, going 8 mi./hr. if it took him 20 min. to get to the store, how many minutes did it take him to get back?