If 25% of a box of drinks is drunk, there are still 18 bottles left. If 50% of the box is drunk, how many bottles are left.
一箱饮料，如果喝掉25%后，还剩下18瓶，如果喝掉50%，还剩下多少瓶．
<gadget id="calculator">25 / 100</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 - (1/4)</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">18 / (3/4)</gadget>
<output>24</output>

<gadget id="calculator">50 / 100</gadget>
<output>1/2 = around 0.5</output>

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

<gadget id="calculator">24 * (1/2)</gadget>
<output>12</output>

<result>12</result>