The meteorological team measured temperatures of 15 degrees, 19 degrees, 16 degrees and 26 degrees at 1 o'clock, 7 o'clock, 13 o'clock and 21 o'clock of the day respectively. Find the average temperature for this day.
气象小组在一天中的1时、7时、13时和21时分别测得气温是15度、19度、16度和26度．求这一天的平均气温．
<gadget id="calculator">15 + 19 + 30 + 16</gadget>
<output>80</output>

<gadget id="calculator">80 / 4</gadget>
<output>20</output>

<result>20</result>