The average of the three numbers is 8.4. The first number is 9.6, which is 1.2 times the second number. What is the third number?
三个数的平均数是8.4，第一个数是9.6，是第二个数的1.2倍，第三个数是多少．
<gadget id="calculator">8.4 * 3</gadget>
<output>25.2</output>

<gadget id="calculator">9.6 / 1.2</gadget>
<output>8</output>

<gadget id="calculator">25.2 - 9.6 - 8</gadget>
<output>7.6</output>

<result>7.6</result>