In a ratio, the product of two inner terms is the smallest prime number, one outer term is (4/9), and the other outer term is what.
在一个比例中，两个内项的积是最小的质数，一个外项是(4/9)，另一个外项是多少．
<gadget id="calculator">4 / 9</gadget>
<output>4/9 = around 0.444444</output>

<gadget id="calculator">2 / (4/9)</gadget>
<output>9/2 = around 4.5</output>

<result>9/2 = around 4.5</result>