On the Arbor Day school planted trees, 408 poplars were planted, 8 more were fir trees (4/5), how many fir trees were planted.
植树节学校植树，植杨树408棵，是杉树的(4/5)多8棵，植杉树多少棵．
<gadget id="calculator">408 - 8</gadget>
<output>400</output>

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

<gadget id="calculator">400 / (4/5)</gadget>
<output>500</output>

<result>500</result>