There are many paintings on display in the elementary school art exhibition, 16 of which are not in the sixth grade, and 15 are not in the fifth grade. Now we know that there are 25 pictures in the fifth and sixth grades, so how many pictures are there in other grades?
小学画展上展出了许多幅画，其中有16幅不是六年级的，有15幅不是五年级的．现知道五、六年级共有25幅画，因此其它年级的画共有多少幅．
<gadget id="calculator">15 - 25</gadget>
<output>-10</output>

<gadget id="calculator">16 + (-10)</gadget>
<output>6</output>

<gadget id="calculator">6 / 2</gadget>
<output>3</output>

<result>3</result>