A bottle of alcohol solution, after pouring out 4 liters, is then filled with water. At this time, the ratio of alcohol to water is 1:9. What is the volume of the bottle?
一瓶酒精溶液，倒出4升后，再用水兑满，这时酒精与水的比是1：9，这个瓶子的容积是多少升？
<gadget id="calculator">1 + 9</gadget>
<output>10</output>

<gadget id="calculator">9 / 10</gadget>
<output>9/10 = around 0.9</output>

<gadget id="calculator">4 / (9/10)</gadget>
<output>40/9 = around 4.444444</output>

<result>40/9 = around 4.444444</result>