Carla needs to dry-clean 80 pieces of laundry by noon. If she starts work at 8 AM, how many pieces of laundry does she need to clean per hour?
First find how many hours Carla has to work: 12:00 - 8:00 = 4 hours.
Then divide the total amount of laundry by the number of hours to find how many pieces Carla has to clean per hour: 80 pieces / 4 hours = 
<gadget id="calculator">80/4</gadget>
<output>20</output>
20 pieces/hour.

<result>20</result>