Given that the average of 15 consecutive natural numbers is 15, what is the average of the first five numbers?
已知15个连续自然数的平均值为15，那么前5个数的平均数是多少．
<gadget id="calculator">8 + 9 + 10 + 11 + 12</gadget>
<output>50</output>

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

<result>10</result>