Xiaoming's family bought two batches of piglets and raised them until October this year. The first batch of 3 heads weighed 66 kg each, and the second batch of 5 heads weighed 42 kg each. What is the average weight of these two batches of pigs raised by Xiaoming's family?
小明家先后买了两批小猪，养到今年10月．第一批的3头每头重66千克，第二批的5头每头重42千克．小明家养的这两批猪平均重多少千克？
<gadget id="calculator">66 * 3</gadget>
<output>198</output>

<gadget id="calculator">42 * 5</gadget>
<output>210</output>

<gadget id="calculator">198 + 210</gadget>
<output>408</output>

<gadget id="calculator">3 + 5</gadget>
<output>8</output>

<gadget id="calculator">408 / 8</gadget>
<output>51</output>

<result>51</result>