Water is composed of hydrogen and oxygen in a weight ratio of 1:8, how many kilograms of oxygen are contained in 45 kg of water?
水是由氢和氧按1：8的重量比化合而成的，45千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">45 * (8/9)</gadget>
<output>40</output>

<result>40</result>