A gardener can purchase two types of fertilizer. A small bag of Jumpstart fertilizer has 3 units of nitrogen, 3 units of phosphorus, and costs $12. A small bag of Growmore fertilizer has 1 unit of nitrogen, 2 units of phosphorus, and costs $9. The farmer must make sure that his crop receives no more than 36 units of nitrogen and no less than 48 units of phosphorus. How many bags of each type of fertilizer should the farmer purchase to minimize the cost? solve and graph and shade a graph