Two water inlet pipes A and B are installed in a pool, and the empty pool can be filled in 24 minutes by opening pipe A alone, and the empty pool can be filled in 18 minutes by opening pipe B alone. Now the pipes A and B are open in turn, according to A 1 minute, B 2 minutes; A 2 minutes, B 1 minute; A 1 minute, B 2 minutes; How many minutes will it take?
一个水池安装了甲乙两个进水管，单开甲管24分钟能把空池注满，单开乙管18分钟能把空池注满．现在甲乙两管轮流开放，按照甲1分钟，乙2分钟；甲2分钟，乙1分钟；甲1分钟，乙2分钟；甲2分钟，乙1分钟…如此交替下去，要灌满一池水共需要多少分钟？
<gadget id="calculator">1 + 2</gadget>
<output>3</output>

<gadget id="calculator">6 * 3</gadget>
<output>18</output>

<gadget id="calculator">1 / 18</gadget>
<output>1/18 = around 0.055556</output>

<gadget id="calculator">1 / 24</gadget>
<output>1/24 = around 0.041667</output>

<gadget id="calculator">(1/18) + (1/24)</gadget>
<output>7/72 = around 0.097222</output>

<gadget id="calculator">(7/72) * 3 * 3</gadget>
<output>7/8 = around 0.875</output>

<gadget id="calculator">1 - (7/8) - (1/24)</gadget>
<output>1/12 = around 0.083333</output>

<gadget id="calculator">(1/12) / (1/18)</gadget>
<output>3/2 = around 1.5</output>

<gadget id="calculator">18 + 1 + (3/2)</gadget>
<output>41/2 = around 20.5</output>

<result>41/2 = around 20.5</result>