The ratio of A, B, and C is 2:7:9, and the average of these three numbers is 24, what is the number of A?
甲、乙、丙三数之比为2：7：9，这三个数的平均数为24，则甲数是多少
<gadget id="calculator">2 + 7 + 9</gadget>
<output>18</output>

<gadget id="calculator">2 / 18</gadget>
<output>1/9 = around 0.111111</output>

<gadget id="calculator">72 * (1/9)</gadget>
<output>8</output>

<result>8</result>