There are 20 poplar trees in the campus, willows are poplars (9/10), pagoda trees are willows (2/3). How many locust trees are there?
校园里有杨树20棵，柳树是杨树的(9/10)，槐树是柳树的(2/3)．槐树有多少棵？
<gadget id="calculator">9 / 10</gadget>
<output>9/10 = around 0.9</output>

<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">20 * (9/10) * (2/3)</gadget>
<output>12</output>

<result>12</result>