The difference between two numbers is 15. If the minuend increases by 2 and the subtrahend decreases by 2, what is the difference?
两个数的差是15，如果被减数增加2，减数减少2，差应该是多少．
<gadget id="calculator">15 + 2 + 2</gadget>
<output>19</output>

<result>19</result>