The sum of two numbers is 7.2, one addend is decreased by 2, and the other is increased by 2.5, what is the sum now
两个数的和是7.2，一个加数减少2，另一个加数增加2.5，那么现在和是多少
<gadget id="calculator">2.5 - 2</gadget>
<output>0.5</output>

<gadget id="calculator">7.2 + 0.5</gadget>
<output>7.7</output>

<result>7.7</result>