The original price of each notebook in the stationery store was 6.50 yuan, but in the promotional activities, the price of 5 notebooks was 28.50 yuan. How much is each copy cheaper now than before?
文具店里笔记本原来每本的售价是6.50元，促消活动中，5本的售价是28.50元．现在每本比原来便宜了多少元？
<gadget id="calculator">28.5 / 5</gadget>
<output>5.7</output>

<gadget id="calculator">6.5 - 5.7</gadget>
<output>0.8</output>

<result>0.8</result>