There are 8 numbers arranged in a column, and their average is 54. The average of the first 5 numbers is 46, and the average of the last 4 numbers is 68. What is the fifth number in this column?
有8个数排成一列，它们的平均数是54．其中前5个数的平均数是46，后4个数的平均数是68，这列数中第5个数是多少．
<gadget id="calculator">46 * 5</gadget>
<output>230</output>

<gadget id="calculator">68 * 4</gadget>
<output>272</output>

<gadget id="calculator">230 + 272</gadget>
<output>502</output>

<gadget id="calculator">54 * 8</gadget>
<output>432</output>

<gadget id="calculator">502 - 432</gadget>
<output>70</output>

<result>70</result>