the cross - section of a cannel is a trapezium in shape . if the cannel is 16 m wide at the top and 4 m wide at the bottom and the area of cross - section is 700 sq m , the depth of cannel is ?
"1 / 2 * d ( 16 + 4 ) = 700 d = 70 answer : e"
divide(divide(divide(700, divide(add(16, 4), const_2)), 4), const_2)