A bundle of wires, half of which is used for the first time is less than 2.5 meters, and the remaining half of which is used for the second time is more than 2.5 meters, leaving 12.5 meters. How many meters is this bundle of wires originally?
一捆电线，第一次用去它的一半少2.5米，第二次用去余下的一半多2.5米，还剩12.5米，这捆电线原来有多少米．
<gadget id="calculator">12.5 + 2.5</gadget>
<output>15</output>

<gadget id="calculator">15 * 2</gadget>
<output>30</output>

<gadget id="calculator">30 - 2.5</gadget>
<output>27.5</output>

<gadget id="calculator">27.5 * 2</gadget>
<output>55</output>

<result>55</result>