A shopkeeper bought 80 kg of rice at a discount of 10%. Besides 1 kg rice was offered free to him on the purchase of every 20 kg rice. If he sells the rice at the marked price, his profit percentage will be:
A car travelled 36 km at 6km/hr faster than the usual speed but it returned the same distance at 6kmph slower than the usual speed. If the total time taken by the car is 8 hrs. For how many hours does the car travelled at faster speed.