When ab=c, if a remains the same and b decreases by 2.6, how much will c increase
a-b=c时，如果a不变，b减少2.6，则c会增加多少
<gadget id="calculator">100 - 47.4</gadget>
<output>52.6</output>

<gadget id="calculator">100 - 50</gadget>
<output>50</output>

<gadget id="calculator">52.6 - 50</gadget>
<output>2.6</output>

<result>2.6</result>