On Arbor Day, the students planted 150 trees, and (1/3) were planted on the first day, among which (2/5) were planted by the sixth graders. How many trees were planted on the first day of sixth grade?
植树节同学们要植150棵树，第一天植了(1/3)，其中的(2/5)是六年级植的．六年级第一天植了多少棵树？
<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">150 * (1/3) * (2/5)</gadget>
<output>20</output>

<result>20</result>