Many paintings were exhibited in a certain primary school art exhibition, among which 18 were not in the sixth grade, and 17 were not in the fifth grade. Now we know that there are 25 paintings in the fifth and sixth grades, so how many paintings are there in other grades?
某小学画展上展出了许多幅画，其中有18幅不是六年级的，有17幅画不是五年级的，现在知道五、六年级共有25幅画，因此其他年级的画共有多少幅．
<gadget id="calculator">17 - 25</gadget>
<output>-8</output>

<gadget id="calculator">18 + (-8)</gadget>
<output>10</output>

<gadget id="calculator">10 / 2</gadget>
<output>5</output>

<result>5</result>