In the school planting, 84 trees were planted in the second grade, twice that of the first grade. The number of trees planted in the third grade was 18 more than the sum of the first and second grades. How many trees were planted in the third grade?
学校植树，二年级植树84棵，是一年级植树的2倍，三年级植树的棵数比一、二年级两个年级植树的总和还多18棵，三年级植树多少棵？
<gadget id="calculator">84 / 2</gadget>
<output>42</output>

<gadget id="calculator">84 + 42</gadget>
<output>126</output>

<gadget id="calculator">126 + 18</gadget>
<output>144</output>

<result>144</result>