There are more plant species (2/3) on the south side of a mountain than on the north side, and there are 20 species of plants on the south side, so how many kinds of plants are there on the north side?
一座山南面的植物种类比北面多(2/3)，南面有20个种类的植物，那么北面有多少种植物？
<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">1 + (2/3)</gadget>
<output>5/3 = around 1.666667</output>

<gadget id="calculator">20 / (5/3)</gadget>
<output>12</output>

<result>12</result>