The cross-section of a water channel is a trapezium in shape. If the channel is 14 meters wide at the top and 8 meters wide at the bottom and the area of cross-section is 990 square meters, what is the depth of the channel (in meters)?	Choose the most appropriate option:
A) 50	B) 60	C) 70	D) 80	E) 90

Rationale: "1 / 2 * d * ( 14 + 8 ) = 990 d = 90 the answer is e ."
Answer: E