A farmer can purchase two types of fertilizer. A 50-lb bag of Crescent fertilizer has 5 units of nitrogen, 15 units of phosphorous, and 5 units of...

A farmer can purchase two types offertilizer. A 50-lb bag of Crescent fertilizer has 5units of nitrogen, 15 units of phosphorous, and 5units of potash and cost $12. A 50 lb bag of Islandfertilizer has 10 units of nitrogen, 10 units ofphosphorous, and 30 units of potash and costs $16.For a given crop the farmer must make sure that itdoes not receive more than 100 units of nitrogenand does not receive less than 120 units each ofphosphorous and potash. How many bags of eachtype of fertilizer should the farmer purchase tominimize his cost?