The survival rate of a batch of saplings is between 80% and 90%. To ensure the survival of 720 saplings, at least how many trees must be planted.
一批树苗的成活率在80%-90%之间，要确保720棵树苗成活，至少要种多少棵树．
<gadget id="calculator">80 / 100</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">720 / (4/5)</gadget>
<output>900</output>

<result>900</result>