A section of steel is 8.4 meters long and sawn into 3 sections, the first section is 1.8 meters, the second section is 2.2 meters, how many meters is the third section?
一段钢材长8.4米，锯成3段，第一段1.8米，第二段2.2米，第三段长多少米？
<gadget id="calculator">1.8 + 2.2</gadget>
<output>4</output>

<gadget id="calculator">8.4 - 4</gadget>
<output>4.4</output>

<result>4.4</result>