An office building is found to gain 2000000Btu/h o heat on a hot summer day over the period 6 am to 6pm. The same building loses 20000 Btu/h over the first 6 hours and the last 6 hours of the same day. What is the total gain or loss of the building for the day in Btu. Than determine the average heat gain for the day in Btu/h.