The question reads: A farmer purchased 100 head of livestock for a total cost of $4000. Prices were as follow: calves, $120 each; lambs, $50 each; piglets, $25 each. If the farmer obtained at least one animal of each type, how many of each did he buy? I obtained that -240 < t < -15.789 but this can't be right as there are way too many t's to check them all. Does any one have a hint or some help?