A tape recorder is now sold for 90 yuan, which is 10% lower than before. How much is the reduction?
一种录音机，现在售机90元，比原来降低10%，降低了多少元．
<gadget id="calculator">10 / 100</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">1 - (1/10)</gadget>
<output>9/10 = around 0.9</output>

<gadget id="calculator">90 / (9/10)</gadget>
<output>100</output>

<gadget id="calculator">100 - 90</gadget>
<output>10</output>

<result>10</result>