A new car is designed for the Indian market such that its mileage at a
particular speed follows a certain relationship with that speed. Also ,
the speed decreases linearly with the mass of the rider while the petrol
consumption per km increases linearly with the mass of rider .Ideally ,
when the mass of the rider is negligible, the speed is 100km/hr and
mileage is 100km/l .When the speed of the Ducati is 50 km/hr , the
mileage is 50 km/l.When the speed of the car is 75 km/hr , the mileage
will be

1) 60
2) 67
3) 72
4) 75