3#
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小 發表於 2015-7-22 03:19 PM (第 2803 天)
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A simple differentiation is whether you purchase the two items toether or not. For example when you purchase a CD, it is not necessary for you to buy the CD player. However when you buy a car, the wheels will(must) be accompanied with. In fact, derived demand for A from B means that A is B's factor of production. On the other hand, joint demand for A and B means they are in the relation of complements