There are a number of water pipes that fill with equal amounts of water per minute. Now open some of the water pipes, after the predetermined time (1/3), and then double the number of open water pipes, the pool can be filled according to the predetermined time. If you open 10 water pipes at the beginning and do not open more water pipes in the middle, you can still fill the pool according to the scheduled time. How many water pipes did you start with?
有一些水管，它们每分钟注水量都相等．现在打开其中若干根水管，经过预定时间的(1/3)，再把打开的水管增加1倍，就能按预定时间注满水池．如果开始就打开10根水管，中途不增开水管，也能按预定时间注满水池．开始打开了几根水管？
<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">1 / 10</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">(1/3) * (1/10)</gadget>
<output>1/30 = around 0.033333</output>

<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">(2/3) * 2 * (1/10)</gadget>
<output>2/15 = around 0.133333</output>

<gadget id="calculator">(1/30) + (2/15)</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">1 / (1/6)</gadget>
<output>6</output>

<result>6</result>