The speed of light in air is 300,000 kilometers per second, and when it travels in glass, the speed will decrease (1/3). What is the speed of light in glass in thousands of kilometers per second?
光在空气中的传播速度是每秒30万千米，在玻璃中传播时，速度会降低(1/3)．光在玻璃中的传播速度是每秒多少万千米？
<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">1 - (1/3)</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">30 * (2/3)</gadget>
<output>20</output>

<result>20</result>