Task: Question Answering
Input (English): Problem: the cross - section of a stream is a trapezium in shape . if the stream is 10 m wide at the top and the area of cross - section is 640 sq m , the depth of stream is 80 m and width at the bottom is ? 
Options: a ) 2 m , b ) 6 m , c ) 4 m , d ) 8 m , e ) 9 m
Output (English): b