A power plant generated an average of 200,000 kWh per day in the first 12 days of June, and an average of 250,000 kWh in the last 18 days. In June, how many tens of thousands of kWh was generated on average every day.
某发电厂6月份的前12天平均每天发电20万度，后18天平均每天发电25万度．6月份平均每天发电多少万度．
<gadget id="calculator">20 * 12</gadget>
<output>240</output>

<gadget id="calculator">25 * 18</gadget>
<output>450</output>

<gadget id="calculator">240 + 450</gadget>
<output>690</output>

<gadget id="calculator">690 / 30</gadget>
<output>23</output>

<result>23</result>