There are 50 black rabbits in the farm, white rabbits are 80% of black rabbits, and 62.5% of gray rabbits, how many gray rabbits are there?
饲养场里黑兔50只，白兔是黑兔的80%，又是灰兔的62.5%，灰兔有多少只．
<gadget id="calculator">80 / 100</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">62.5 / 100</gadget>
<output>0.625</output>

<gadget id="calculator">(4/5) / 0.625</gadget>
<output>1.28</output>

<gadget id="calculator">50 * 1.28</gadget>
<output>64</output>

<result>64</result>