The ratio of the three numbers A, B, and C is 2:3:5, and their average is 20. What is A?
甲乙丙三个数的比是2：3：5，它们的平均数是20，甲是多少．
<gadget id="calculator">3 / 10</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">60 * (3/10)</gadget>
<output>18</output>

<result>18</result>