The school carried out the activity of learning from Lei Feng to do good deeds. The fourth grade did 84 good deeds, twice that of the third grade. The fifth grade did 18 more than the sum of the third and fourth grades. How many good deeds did the fifth grade do?
学校开展学雷锋做好事活动，四年级做好事84件，是三年级做的2倍，五年级做的比三、四两个年级的总和还多18件，五年级做好事多少件？
<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>