Li Li bought 5 copies of "YiDianTong" and "Divide Three from One", paid a total of 90 yuan, got back 8.5 yuan, each copy of "YiDianTong" was 6.8 yuan, how much was each copy of "Diamond from One"?
李利买来《一点通》和《举一反三》各5本，共付90元，找回8.5元，每本《一点通》6.8元，每本《举一反三》多少元？
<gadget id="calculator">90 - 8.5</gadget>
<output>81.5</output>

<gadget id="calculator">81.5 / 5</gadget>
<output>16.3</output>

<gadget id="calculator">16.3 - 6.8</gadget>
<output>9.5</output>

<result>9.5</result>