来自《耶鲁大学开放课程：金融理论 第3集 第3集》

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  So now I'm going to solve this.
  我现在要解出它
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  So how can I do this?
  我怎么才能解开呢
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  I want to do the same trick as before.
  我会用与前面一样的技巧
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  I now want to solve--so let's take P_Y to be 1 like
  我现在要做了 我们假设P_Y=1
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  I did before,take P_Y to be 1.
  我前面也是这样做的 P_Y=1
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  So let's just solve this equation, solve for X.
  让我们解出这个等式 解出X
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  It's not going to be so easy to do this.
  这个可不容易
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  So now there's a tremendous trick here.
  所以我们需要一个很大的技巧
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  What does this say if I rewrite this?
  如果我把它在写一遍会怎么样呢
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  I can bring the X down here and I get P_X times X.
  把X移下来 得到P_X乘以X
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  And I can bring the Y down here and I get P_Y times Y.
  我还可以把Y移下来 就得到P_Y乘以Y
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  So it says that the amount you spend on X relative to 3
  因此你花在X上的钱相比较于