When an elephant is drinking water from a small pool, a group of giraffes come to drink with it. If there are 10 giraffes, the water will be consumed in 5 minutes; if there are 15 giraffes, the water will be consumed in 4 minutes. drink up. So if there are 30 giraffes, how many minutes will the water be drunk.
一头大象正在一个小水池边喝水时来了一群长颈鹿和它一起喝水，如果有10只长颈鹿，则5分钟后水将被喝光；如果有15只长颈鹿，则4分钟后水将被喝光．那么如果有30只长颈鹿，多少分钟后水将被喝光．
<gadget id="calculator">1 / 10</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">(1/4) - (1/5)</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">15 - 10</gadget>
<output>5</output>

<gadget id="calculator">(1/20) / 5</gadget>
<output>1/100 = around 0.01</output>

<gadget id="calculator">(1/100) * 30</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">(1/10) + (3/10)</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 / (2/5)</gadget>
<output>5/2 = around 2.5</output>

<result>5/2 = around 2.5</result>