Task: Question Answering
Input (English): Problem: a car ferry can hold up to 60 tons of cargo . what is the greatest number of vehicles that the ferry can carry if half the vehicles are cars with an average ( arithmetic mean ) weight of 0.75 tons and half of the vehicles are trucks with an average ( arithmetic mean ) weight of 5 tons ? 
Options: a ) 10 , b ) 12 , c ) 16 , d ) 18 , e ) 20
Output (English): e