The ratio of the three numbers A, B and C is 11:12:15. Given that the number B is 45 less than the number C, what is the number A?
甲、乙、丙三个数的比是11：12：15，已知乙数比丙数少45，则甲数是多少．
<gadget id="calculator">15 - 12</gadget>
<output>3</output>

<gadget id="calculator">45 / 3</gadget>
<output>15</output>

<gadget id="calculator">15 * 11</gadget>
<output>165</output>

<result>165</result>