There are 4 fewer white rabbits than black rabbits, and 1/5 fewer white rabbits than black rabbits. How many white rabbits are there?
白兔比黑兔少4只，白兔比黑兔少(1/5)，白兔有多少只？
<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">4 / (1/5)</gadget>
<output>20</output>

<gadget id="calculator">20 - 4</gadget>
<output>16</output>

<result>16</result>