When 200 gallons of oil were removed from a tank, the volume of oil left in the tank was \frac 3 7 of the tank's capacity. What was the tank's capacity?
(1)Before the 200 gallons were removed, the volume of oil in the tank was \frac1 2 of the tank's capacity.
(2)After the 200 gallons were removed, the volume of oil left in the tank was 1,600 gallons less than the tank's capacity.