The average of the three numbers A, B, and C is 102. The number of B is 1.5 times that of A, and the number of C is 3.5 times that of A. What is the number of A?
甲、乙、丙三个数的平均数是102，乙数是甲数的1.5倍，丙数是甲数的3.5倍，甲数是多少？
<gadget id="calculator">102 * 3</gadget>
<output>306</output>

<gadget id="calculator">1 + 1.5 + 3.5</gadget>
<output>6</output>

<gadget id="calculator">306 / 6</gadget>
<output>51</output>

<result>51</result>