Today, a tank contains 6,600 gallons of water. For the past three days, 210 gallons of water was pumped out of the tank each day. What was the volume of water in the tank 3 days ago?
Compute the total amount pumped out in the last three days:
210 gallons/day x 3 days = 630 gallons
Add the volume pumped out (removed) to the volume today:
Volume today = 6600 gallons
Volume pumped out = 630 gallons
Volume 3 days ago = 6600 gallons + 630 gallons = 7230 gallons
Thus the volume three days ago was 7230 gallons.