The number A is 40, which is 80% of the number B, and how much more the number B is than the number A.
甲数是40，它是乙数的80%，乙数比甲数多多少．
<gadget id="calculator">80 / 100</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">40 / (4/5)</gadget>
<output>50</output>

<gadget id="calculator">50 - 40</gadget>
<output>10</output>

<result>10</result>