In a proportional formula, two internal terms are examples of each other, one external term is (3/4), and the other external term is how much.
一个比例式中，两个内项互为例数，一个外项是(3/4)，另一个外项是多少．
<gadget id="calculator">3 / 4</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">1 / (3/4)</gadget>
<output>4/3 = around 1.333333</output>

<result>4/3 = around 1.333333</result>