Water is composed of hydrogen and oxygen in a weight ratio of 1:8. How many kilograms of oxygen are contained in 72 kilograms of water?
水是由氢和氧按1：8的重量比化合而成的，72千克水中，含氧多少千克．
<gadget id="calculator">1 + 8</gadget>
<output>9</output>

<gadget id="calculator">8 / 9</gadget>
<output>8/9 = around 0.888889</output>

<gadget id="calculator">72 * (8/9)</gadget>
<output>64</output>

<result>64</result>