The average of five numbers is 70, the average of the first three numbers is 52, and the average of the last three numbers is 83. What is the third number.
五个数排成一行，平均数是70，前三个数的平均数是52，后三个数的平均数是83．第三个数是多少．
<gadget id="calculator">52 * 3</gadget>
<output>156</output>

<gadget id="calculator">83 * 3</gadget>
<output>249</output>

<gadget id="calculator">70 * 5</gadget>
<output>350</output>

<gadget id="calculator">249 - 350</gadget>
<output>-101</output>

<gadget id="calculator">156 + (-101)</gadget>
<output>55</output>

<result>55</result>