Planting a kind of sapling, the minimum survival rate is 50% and the maximum is 80%. If you want to guarantee the survival of 2400 trees, how many trees should you plant at least.
栽一种树苗，成活率最低是50%，最高是80%，如果想保证种活2400棵树，最少种树多少棵．
<gadget id="calculator">80 / 100</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">2_400 / (4/5)</gadget>
<output>3_000</output>

<result>3_000</result>