Problem: the cross - section of a cannel is a trapezium in shape . if the cannel is 14 m wide at the top and 4 m wide at the bottom and the area of cross - section is 380 sq m , the depth of cannel is ?
Rationale: "1 / 2 * d ( 14 + 4 ) = 380 d = 42 answer : d"
annotated_formula: divide(divide(divide(380, divide(add(14, 4), const_2)), 4), const_2)