1. Total time of trip from Mumbai to Pune =$\frac{Distance}{speed}$=$\frac{200}{60}$ Hour
At speed of 60 km/hr petrol consumption rate=4 Litre / hour
Total amount of petrol consumed for the journey=$\frac{200}{60}$ * 4 =13.33
Hence,Option (2) 13.33 Litres .
2. (1) When we increase the speed from 60 km/hr to 80 km/hr then petrol consumption will increase by 6.42 Litres.
$\frac{200}{80}$ * 7.9 - $\frac{200}{60}$ * 4 = 6.42
(2) When we decreased the speed from 60 km/hr to 40 km/hr then petrol consumption will decrease by 0.83 Litres.
$\frac{200}{60}$ * 4 - $\frac{200}{40}$ * 7.9 = 0.83
(3) we can't reduce the petrol consumption by Maintaining the speed at 60 km/hour.
Hence,Option (2) Decrease the speed .