Three farmers paid $1,000 for a small pasture. One farmer grazed his nine mules, another his twelve cows for twice the time and the last man put in some goats for two and half times as the second man's cows and paid half the cost of the pasture. Can you find out how many goats did the last man have, if six cows eat as much as four mules, and ten goats as much as three cows ? And how much did the first and second man each pay?