How Many Minutes will it Take to Load 6 1/2 Trucks?

If it Takes 42 Minutes to Load 3 1/2 Trucks, How Many Minutes will it Take to Load 6 1/2 Trucks?

if it takes 42 minutes to load 3 1/2 trucks, how many minutes will it take to load 6 1/2 trucks?, Answer is “78 minutes”.