The ratio of the three numbers A, B, and C is 2:3:5, and the average number is 30. What is A?
甲乙丙三个数之比是2：3：5，平均数为30，甲是多少．
<gadget id="calculator">2 + 3 + 5</gadget>
<output>10</output>

<gadget id="calculator">2 / 10</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">30 * 3 * (1/5)</gadget>
<output>18</output>

<result>18</result>