Task: Question Answering
Input (English): Problem: if a child walks at the rate of 5 m / min from his home , he is 6 minutes late for school , if he walks at the rate of 7 m / min he reaches half an hour earlier . how far is his school from his home ? 
Options: a ) 450 min , b ) 540 min , c ) 630 min , d ) 360 min , e ) none of these
Output (English): c