In proportion, the product of two outer terms is 1, one inner term is (3/5), and the other inner term is what.
在比例中，两个外项的积是1，其中一个内项是(3/5)，另一个内项是多少．
<gadget id="calculator">3 / 5</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">1 / (3/5)</gadget>
<output>5/3 = around 1.666667</output>

<result>5/3 = around 1.666667</result>