The average of the three numbers A, B, and C is 20, and the ratio of the three numbers A, B, and C is 1:2:3. What is the number of A?
甲、乙、丙三个数的平均数是20，甲、乙、丙三个数的比是1：2：3，则甲数是多少
<gadget id="calculator">1 / 6</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">20 * 3 * (1/6)</gadget>
<output>10</output>

<result>10</result>