Xiaolan found a row of telephone poles standing equidistantly beside the road. It took her 7 minutes to walk from the first pole to the 15th pole at a uniform speed, and then she continued to walk forward, walked a few more poles, and then went back. It took 30 minutes for her to walk back to the fifth pole. So how many telegraph poles did Xiaolan walk to and started to walk back.
小兰发现公路边等距地立着一排电线杆．她用均匀的速度从第1根电线杆走到第15根电线杆用了7分钟时间，接着她继续往前走，又走了若干根电线杆后就往回走．当她走回到第5根电线杆时一共用了30分钟．那么小兰是走到第多少根电线杆是开始往回走的．
<gadget id="calculator">15 - 1</gadget>
<output>14</output>

<gadget id="calculator">14 / 7</gadget>
<output>2</output>

<gadget id="calculator">30 * 2</gadget>
<output>60</output>

<gadget id="calculator">1 + 5 + 60</gadget>
<output>66</output>

<gadget id="calculator">1 + 1</gadget>
<output>2</output>

<gadget id="calculator">66 / 2</gadget>
<output>33</output>

<result>33</result>