In a ratio, the two outer terms are exactly reciprocals of each other, one of the inner terms is (2/3), and the other inner term is how much.
一个比例里，两个外项正好互为倒数，其中一个内项是(2/3)，另一个内项是多少．
<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">1 / (2/3)</gadget>
<output>3/2 = around 1.5</output>

<result>3/2 = around 1.5</result>