The average of 5 natural numbers is 68. If one of the numbers increases by 20%, the average becomes 70. What is the increased number?
5个自然数的平均数是68，若其中一个数增加20%，则平均数变为70，增加的那个数原来是多少．
<gadget id="calculator">70 * 5</gadget>
<output>350</output>

<gadget id="calculator">68 * 5</gadget>
<output>340</output>

<gadget id="calculator">350 - 340</gadget>
<output>10</output>

<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">10 / (1/5)</gadget>
<output>50</output>

<result>50</result>