A snowstorm began at noon, and snow had fallen at a constant rate per hour. If the depth of the snow was 21 inches at 5 o’clock in the afternoon and 33 inches at 9 o’clock at night, how much snow was on the ground BEFORE the snowstorm began? If the snow continues falling at the constant rate, how much snow will there be if the snow stops at 2 o’clock in the morning?