The number A is the number B (4/5), and the number B is the number A.
甲数是乙数的(4/5)，乙数是甲数的多少．
<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">1 / (4/5)</gadget>
<output>5/4 = around 1.25</output>

<result>5/4 = around 1.25</result>