By weight, 1st fertilizer is 20% potassium, 30% nitrogen and 50% phosphorus. 2nd fertilizer has percent of 10, 30, and 60 respectively, and 3rd fertilizer has percent of 0, 40, and 60 respectively. How much of each should be mixed to get 200lb of fertilizer with percents of 10.5, 32, and 57.5 respectively.