When two numbers are added, one number is increased by 0.8. The other number is reduced by 2.6, and by how much
两个数相加，一个数增加0.8．另一个数减少2.6，和减少多少
<gadget id="calculator">2.6 - 0.8</gadget>
<output>1.8</output>

<result>1.8</result>