On Arbor Day last year, Guangming Primary School planted a total of 540 poplars and pagoda trees, among which poplars accounted for two thirds of these two types of trees, and later some pines were planted, poplars accounted for three fifths of these three types of trees. How many pine trees?
去年植树节，光明小学种了杨树和槐树共540棵，其中杨树占这两种树的(2/3)，后来又种了一些松树，杨树占这三种树的(3/5)，后来种了多少棵松树？
<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">3 / 5</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">(2/3) / (3/5)</gadget>
<output>10/9 = around 1.111111</output>

<gadget id="calculator">540 * (10/9)</gadget>
<output>600</output>

<gadget id="calculator">600 - 540</gadget>
<output>60</output>

<result>60</result>