In a multiplication equation, if one factor increases by 4, the product increases by 12; if the other factor increases by 4, the product increases by 168. What is the correct product?
一道乘法算式，如果一个因数增加4，积就增加了12；如果另一个因数增加4，积就增加了168．正确的积应是多少？
<gadget id="calculator">12 / 4</gadget>
<output>3</output>

<gadget id="calculator">168 / 4</gadget>
<output>42</output>

<gadget id="calculator">3 * 42</gadget>
<output>126</output>

<result>126</result>