The store sells a tape recorder, the original price is 400 yuan each. It is now on sale at a 10% discount. How much is it cheaper than before?
商店出售一种录音机，原价每台400元．现在打九折出售，现在比原来便宜了多少元？
<gadget id="calculator">90 / 100</gadget>
<output>9/10 = around 0.9</output>

<gadget id="calculator">1 - (9/10)</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">400 * (1/10)</gadget>
<output>40</output>

<result>40</result>