Problem: 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 ) ?
Rationale: "1 / 2 * d * ( 14 + 8 ) = 990 d = 90 the answer is e ."
annotated_formula: divide(990, divide(add(14, 8), const_2))