After the price of a mobile phone is reduced, it only sells for 1,800 yuan, and the price is only 9/10 of the original price. How much is the price cut from the original price?
一部手机降价后只卖1800元，售价只有原来的9/10，比原来降价了多少元？
<gadget id="calculator">9 / 10</gadget>
<output>9/10 = around 0.9</output>

<gadget id="calculator">1_800 / (9/10)</gadget>
<output>2_000</output>

<gadget id="calculator">2_000 - 1_800</gadget>
<output>200</output>

<result>200</result>