There are three wires, the length of the first wire is 8 meters, the length of the second wire is 12 meters, the length of the third wire is 2 meters less than the sum of the first two wires, what is the length of the third wire?
有三根铁丝，第一根长8米，第二根长12米，第三根的长度比前两根的总和少2米，第三根长多少米．
<gadget id="calculator">12 - 2</gadget>
<output>10</output>

<gadget id="calculator">8 + 10</gadget>
<output>18</output>

<result>18</result>