Xiaohong bought a copy of "Story King", paid the salesperson 10 yuan, and got back 2.45 yuan. How much is a copy of "Story King"?
小红买了一本《故事大王》，付给营业员10元钱，找回2.45元，一本《故事大王》多少钱？
<gadget id="calculator">10 - 2.45</gadget>
<output>7.55</output>

<result>7.55</result>