Task: Question Answering
Input (English): Problem: the cross - section of a cannel is a trapezium in shape . if the cannel is 9 m wide at the top and 7 m wide at the bottom and the area of cross - section is 560 sq m , the depth of cannel is ? 
Options: a ) 39 , b ) 28 , c ) 70 , d ) 80 , e ) 71
Output (English): c