Few decades ago, when cars were not very common, there was a man named Robin. He had a horse, somehow named Batman. Robin’s job was to deliver top quality hay bushels (horse food) from a farm to a horse trade center, located few hundred miles away from the farm. It took few days for each journey between farm and the trade center, with a desert in between.
One fine day, the farm owner gave Robin 100 bushels to transport to the trade center. The trade owner, Mr. Joker, was to give Robin 3 cents for a bushel each. As a part of contract, for each bushel missed, Robin had to pay a fine of 9 cents.
Robin started early morning next day for the trace center. Since the journey was long, Robin had the problem of feeding Batman. Finding no other way, Robin decided to use the bushels he was carrying. Batman ate 1 bushel every day.
Finally, Robin got 240 cents from the trade owner.
How many days did it take Robin and Batman to reach the trade center from the farm?