5 numbers are written in a row, the average of the first 3 numbers is 15, and the average of the last two numbers is 10, what is the average of these 5 numbers?
5个数写成一排，前3个数的平均值是15，后两个的数的平均值是10，这五个数的平均的值是多少．
<gadget id="calculator">3 * 15</gadget>
<output>45</output>

<gadget id="calculator">2 * 10</gadget>
<output>20</output>

<gadget id="calculator">45 + 20</gadget>
<output>65</output>

<gadget id="calculator">3 + 2</gadget>
<output>5</output>

<gadget id="calculator">65 / 5</gadget>
<output>13</output>

<result>13</result>