When two numbers are multiplied, if one factor increases by 4 and the other factor remains unchanged, then the product increases by 36; if one factor remains unchanged and the other factor decreases by 4, then the product decreases by 200. What is the original product?
两个数相乘，如果一个因数增加了4，另外一个因数不变，那么积增加36；如果一个因数不变，另一个因数减少4，那么积就减少200．原来的积是多少？
<gadget id="calculator">200 / 4</gadget>
<output>50</output>

<gadget id="calculator">50 * 9</gadget>
<output>450</output>

<result>450</result>