Mao Mao and Xiao Bing bought the same exercise book in the same store, Mao Mao bought 6 books, and Xiao Bing bought 4 books, and Mao Mao paid 3 yuan and 80 cents more than Xiao Bing. How much is the price of each exercise book.
毛毛和小兵在同一个商店买同一种练习本，毛毛买了6本，小兵买了4本，毛毛比小兵多付了3元8角钱．每本练习本的价格是多少钱．
<gadget id="calculator">8 / 10</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">3 + (4/5)</gadget>
<output>19/5 = around 3.8</output>

<gadget id="calculator">6 - 4</gadget>
<output>2</output>

<gadget id="calculator">(19/5) / 2</gadget>
<output>19/10 = around 1.9</output>

<result>19/10 = around 1.9</result>