It takes 20 minutes to use pump A to drain a well, and 30 minutes to use pump B to dry it up without water seepage. Now, because of the seepage at the bottom of the well, and the amount of seepage water per minute is equal, using the two pumps together for 18 minutes is just enough to drain the well. ． If the water is pumped by A water pump alone, how long will it take to drain the water?
抽干一口井，在无渗水的情况下，用甲抽水机要20分钟，用乙抽水机要30分钟，现因井底渗水，且每分钟渗水量相等，用两台抽水机合抽18分钟正好抽干．如单独用甲抽水机抽水，多少分钟把水抽干？
<gadget id="calculator">1 / 20</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">1 / 30</gadget>
<output>1/30 = around 0.033333</output>

<gadget id="calculator">(1/20) + (1/30)</gadget>
<output>1/12 = around 0.083333</output>

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

<gadget id="calculator">(3/2) - 1</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">(1/2) / 18</gadget>
<output>1/36 = around 0.027778</output>

<gadget id="calculator">(1/20) - (1/36)</gadget>
<output>1/45 = around 0.022222</output>

<gadget id="calculator">1 / (1/45)</gadget>
<output>45</output>

<result>45</result>