An iron pipe is cut off 3 meters for the first time, and the remaining half is cut off for the second time, leaving 6 meters. What is the original length of the iron pipe?
一根铁管，第一次截去3米，第2次截去剩下的一半，还剩下6米，这根铁管原来长多少米．
<gadget id="calculator">6 * 2</gadget>
<output>12</output>

<gadget id="calculator">12 + 3</gadget>
<output>15</output>

<result>15</result>