When multiplying two numbers, if a factor increases by 4, the product increases by 568; if a factor decreases by 7, the product decreases by 140. What is the product of the original two factors?
两个数相乘，如果一个因数增加4，那么积就增加568；如果一个因数减少7，那么积就减少140．原来两个因数的积是多少？
<gadget id="calculator">568 / 4</gadget>
<output>142</output>

<gadget id="calculator">140 / 7</gadget>
<output>20</output>

<gadget id="calculator">142 * 20</gadget>
<output>2_840</output>

<result>2_840</result>