A jeweler sells gems at a cost in dollars per centigram that is 4 more than 6 times the weight of the gem in centigrams.
Thus, a gem that weighs w centigrams will be sold at a price of 6w + 4 dollars per centigram - meaning that a larger,
heavier gem will cost more per centigram than a smaller gem. If the jeweler sold a single gem for about $2500, what
did the gem weigh to the nearest centigram?