The school organized students in the fourth, fifth and sixth grades to participate in tree planting. A total of 120 trees were planted, among which (2/5) were planted by the sixth grade, (3/5) were planted by the fifth grade, and the rest were planted by the fourth grade. How many trees are planted in fourth grade?
学校组织四、五、六年级的同学参加植树，一共植120棵树，其中(2/5)是六年级植的，(3/5)是五年级植的，剩下的由四年级植．四年级植树多少棵？
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

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

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

<gadget id="calculator">1 - 1</gadget>
<output>0</output>

<gadget id="calculator">120 * 0</gadget>
<output>0</output>

<result>0</result>