A and B brought the same amount of money to buy exercise books together. A spent all his money and borrowed 1 yuan and 2 cents from B, and bought 12 copies. The remaining money of B can just buy 9 books. What is the unit price of the exercise book?
甲、乙两人带着相同数量的钱一起去买练习本，甲花光了自己所有的钱，并向乙借了1元2角，刚好买了12本．乙剩下的钱恰好还可以买9本．练习本的单价是多少．
<gadget id="calculator">2 / 10</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 + (1/5)</gadget>
<output>6/5 = around 1.2</output>

<gadget id="calculator">(6/5) * 2</gadget>
<output>12/5 = around 2.4</output>

<gadget id="calculator">12 - 9</gadget>
<output>3</output>

<gadget id="calculator">(12/5) / 3</gadget>
<output>4/5 = around 0.8</output>

<result>4/5 = around 0.8</result>