A pool has one inlet pipe and three same outlet pipes. First open the water inlet pipe, wait for some water in the pool, and then open the water outlet pipe. If 2 outlet pipes are opened at the same time, the pool will be empty after 8 minutes; if 3 outlet pipes are opened at the same time, the pool will be empty after 5 minutes. So how many minutes later does the outlet pipe open than the inlet pipe?
一个水池装一个进水管和三个同样的出水管．先打开进水管，等水池存了一些水后，再打开出水管．如果同时打开2个出水管，那么8分钟后水池空；如果同时打开3个出水管，那么5分钟后水池空．那么出水管比进水管晚开多少分钟？
<gadget id="calculator">2 * 8</gadget>
<output>16</output>

<gadget id="calculator">3 * 5</gadget>
<output>15</output>

<gadget id="calculator">16 - 15</gadget>
<output>1</output>

<gadget id="calculator">8 - 5</gadget>
<output>3</output>

<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">2 - (1/3)</gadget>
<output>5/3 = around 1.666667</output>

<gadget id="calculator">8 / (1/3)</gadget>
<output>24</output>

<gadget id="calculator">(5/3) * 24</gadget>
<output>40</output>

<result>40</result>