A farmer has several packages of fertilizer for his new grain crop. the old packages contains 40 pounds of long-term growth supplement and 70 pounds of weed killer. the new packages contain 65 pounds of long-term growth supplement and 45 pounds of weed killer. using past experience, the farmer estimates that he needs 3475 ponds of long-term growth supplement and 3675 ponds of weed killer for the fields. how many old packages of fertilizer and how may new packages of fertilizer should he use? The farmer needs___ bags of old fertilizer and ___ bags of new fertilizer.