During the Shanghai World Expo, major hotels have launched preferential policies. Among them, a preferential room in a five-star hotel is 850 yuan per room per night, which is 1/6 cheaper than before, and a preferential room in a four-star hotel is 450 yuan per room per night, which is 25% cheaper than before. How much cheaper is the room in a five-star hotel than in the five-star hotel?
上海世博会间，各大酒店纷纷推出优惠政策．其中某五星级酒店优惠房每间每晚850元，比原来便宜了(1/6)，某四星级酒店优惠房每间每晚450元，比原来便宜了25%，原来该四星级酒店这种客房比该五星级酒店这种客房每间每晚便宜多少元？
<gadget id="calculator">1 / 6</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">1 - (1/6)</gadget>
<output>5/6 = around 0.833333</output>

<gadget id="calculator">850 / (5/6)</gadget>
<output>1_020</output>

<gadget id="calculator">1_020 * (1/6)</gadget>
<output>170</output>

<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">450 / (3/4)</gadget>
<output>600</output>

<gadget id="calculator">600 * (1/4)</gadget>
<output>150</output>

<gadget id="calculator">170 - 150</gadget>
<output>20</output>

<result>20</result>