Li Qiang's average math score in the first two tests was 78 points. After the third test, the average score of the three tests was 84 points. How many points did he get in the third test?
李强前两次的数学平均成绩为78分，第三次测试后，三次的平均成绩为84分，第三次得了多少分？
<gadget id="calculator">84 * 3</gadget>
<output>252</output>

<gadget id="calculator">78 * 2</gadget>
<output>156</output>

<gadget id="calculator">252 - 156</gadget>
<output>96</output>

<result>96</result>