When multiplying two numbers, if one factor increases by 2, the product increases by 1.4; if the other factor decreases by 6, the product decreases by 7.8. What is the sum of these two numbers?
两个数相乘，如果一个因数增加2，积就增加1.4；如果另一个因数减少6，积就减少7.8．这两个数的和是多少？
<gadget id="calculator">1.4 / 2</gadget>
<output>0.7</output>

<gadget id="calculator">7.8 / 6</gadget>
<output>1.3</output>

<gadget id="calculator">0.7 + 1.3</gadget>
<output>2</output>

<result>2</result>