Read the following passage and solve the questions based on it.
For a motorist, there are three ways of going from city A to city C by a 20 km long, toll highway the toll for which is
Rs 25 per entry; a 10 km long tunnel between the two cities, the toll for which is Rs 40 per entry; and a two-lane, toll-free highway which goes 30 km east to city B and then 20 km north-west to city C.
The running cost of the motorist Re 1/km.
Due to CNG, the cost of the motorist has reduced to
Rs 0.5/km. Which of the following is the cheapest way to go from city A to city C?