The original price of a learning machine is 800 yuan, and now it is sold at a 10% discount. How much is it cheaper than before?
一台学习机原价800元，现在打九折出售，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">800 * (9/10)</gadget>
<output>720</output>

<gadget id="calculator">800 - 720</gadget>
<output>80</output>

<result>80</result>