The number A is 80% of the number B, then how much more the number B is than the number A.
甲数是乙数的80%，那么乙数比甲数多多少．
<gadget id="calculator">5 - 4</gadget>
<output>1</output>

<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<result>1/4 = around 0.25</result>