A tea bag producer produces two brands of Chinese diet tea bag, A and B, of mixed herbs P and Q together. BrandA tea bag contains 20 g of herbs P and 10 g of herbs Q. Brand B tea bag contains 50 g of herbs P and 70 g of herbs Q. The producer have 12 kg of herbs P, 15 kg of herbs Q and 16 paper boxes. Each paper box can pack 25 brand A diet tea bags or 20 brand B tea bags. The profits generated by a box of brand A tea bag and a box of brand B tea bag are $20 and $30 respectively. Suppose x boxes of brandA tea bag and y boxes of brand B tea bag are produced. (3) Write down all the constraints. (b) Using the graph paper provided, (i) Find x and y so that the profit will be a maximum. (ii) Hence find the maximum profit. (c) If the number of boxes of brand A tea bag is smaller that that of brand B tea bag, find the greatest profit