The average of the three numbers is 12, and their ratio is 4:5:3. What is the smallest number?
三个数字的平均数是12，它们的比是4：5：3，最小的数是多少．
<gadget id="calculator">4 + 5 + 3</gadget>
<output>12</output>

<gadget id="calculator">3 / 12</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">12 * 3 * (1/4)</gadget>
<output>9</output>

<result>9</result>