The sixth-grade students planted castor beans. The first class planted 120 plants, which was less than the second class (2/5). How many trees did the two classes plant in total?
六年级同学种蓖麻，一班种了120棵，比二班种的棵数少(2/5)．二个班一共种了多少棵？
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 - (2/5)</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">120 / (3/5)</gadget>
<output>200</output>

<gadget id="calculator">200 + 120</gadget>
<output>320</output>

<result>320</result>