Exercise 3. Suppose you are about to buy 10 kg of oranges and 8 kg of apples. The price of oranges are $10/Kg and apples are also $10/Kg. Considering that you have $180 to spend, you are convinced that you have made the best possible choice. When he is about to pay, his brother tries to convince him that he must return some apples and replace them with additional units of oranges. This produces a disagreement between the two brothers. Explain, using graphs, why this disagreement occurs