The taxi charges in a city comprise of a fixed charge, together with the charge of the distance covered. For a journey of 16 km, the charges paid are Rs 156 and for a journey of 24 km, the charges paid are Rs 204. What will a person have to pay for travelling a distance of 30 km? (a) Rs 236     (b) Rs 240    (c) Rs 248   (d) Rs 252