A piece of iron wire is 50.7 meters long, 3.2 meters are used for the first time, and 2.1 meters are used for the second time three times more than the first time, how many meters are left?
一根铁丝长50.7米，第一次用去3.2米，第二次用去的比第一次的3倍多2.1米，还剩下多少米？
<gadget id="calculator">3.2 * 3</gadget>
<output>9.6</output>

<gadget id="calculator">9.6 + 2.1</gadget>
<output>11.7</output>

<gadget id="calculator">3.2 + 11.7</gadget>
<output>14.9</output>

<gadget id="calculator">50.7 - 14.9</gadget>
<output>35.8</output>

<result>35.8</result>