The reciprocal of the number A is 20, the number B is (4/5) of the number A, what is the number B.
甲数的倒数是20，乙数是甲数的(4/5)，乙数是多少．
<gadget id="calculator">1 / 20</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">(1/20) * (4/5)</gadget>
<output>1/25 = around 0.04</output>

<result>1/25 = around 0.04</result>