A, B, and C each pay the same amount of money to buy exercise books. When distributing the exercise books, A gets 12 more than C, and B gets 9 more than C. At the time of settlement, A gives C 15 yuan, and B should give How much is C?
甲、乙、丙3人各出同样的钱买练习本，在分练习本时，甲比丙多拿12本，乙比丙多拿9本，结算时，甲给丙15元，乙应给丙多少元？
<gadget id="calculator">15 / 12</gadget>
<output>5/4 = around 1.25</output>

<gadget id="calculator">(5/4) * 9</gadget>
<output>45/4 = around 11.25</output>

<result>45/4 = around 11.25</result>