The number A is 15 greater than the number B, the number B is 16 less than the number C, and the number C is 18. What is the number A?
甲数比乙数大15，乙数比丙数小16，丙数是18，甲数是多少．
<gadget id="calculator">18 - 16</gadget>
<output>2</output>

<gadget id="calculator">2 + 15</gadget>
<output>17</output>

<result>17</result>