The difference between the two numbers is 16.78. If the minuend is reduced by 3.8 and the subtrahend is increased by 4.9, what is the difference?
两个数的差是16.78，如果被减数少3.8，减数增加4.9，这时的差是多少．
<gadget id="calculator">3.8 + 4.9</gadget>
<output>8.7</output>

<gadget id="calculator">16.78 - 8.7</gadget>
<output>8.08</output>

<result>8.08</result>