题目:https://goo.gl/XZz4T3 Refer to Figure 3-8. If the production possibilities frontiers shown are each for one day of production, then which of the following combinations of coffee and soybeans could Chile and Colombia together make in a given day? A. 4 pounds of coffee and 16 pounds of soybeans B. 8 pounds of coffee and 15 pounds of soybeans C. 16 pounds of coffee and 10 pounds of soybeans D. 24 pounds of coffee and 4 pounds of soybeans 我的想法: 当初是想说，将两个直线方程式合并後，得到新的方程式 再将选项的数字代入验证是不是正确的答案，但一直找不 到方法做，问友人也只知道答案用凑的出来是A，好苦恼 求版上的大大为我解答QQ --

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