Xiao Ming’s family used 320 kWh of electricity in the first 4 months of this year, and 409.6 kWh in the next 8 months. How much electricity does it use on average every month?
小明家今年前4个月用电320千瓦时，后8个月用电409.6千瓦时，平均每个月用多少电？
<gadget id="calculator">320 + 409.6</gadget>
<output>729.6</output>

<gadget id="calculator">4 + 8</gadget>
<output>12</output>

<gadget id="calculator">729.6 / 12</gadget>
<output>60.8</output>

<result>60.8</result>