the cross - section of a cannel is a trapezium in shape . if the cannel is 12 m wide at the top and 5 m wide at the bottom and the area of cross - section is 344 sq m , the depth of cannel is ?
"1 / 2 * d ( 12 + 5 ) = 344 d = 40 answer : d"
divide(divide(divide(344, divide(add(12, 5), const_2)), 5), const_2)