A school holds an art exhibition. A total of 55 paintings from grades five and six participated in the exhibition. In the exhibition, there are 75 pictures for those who are not in the fifth grade, and 80 pictures for those who are not in the sixth grade. How many pictures from other grades participated in the exhibition?
某校举办画展．五、六年级共有55幅画参加展出．画展中不是五年级的有75幅，不是六年级的有80幅．其它年级共有多少幅参加画展？
<gadget id="calculator">80 - 55</gadget>
<output>25</output>

<gadget id="calculator">75 + 25</gadget>
<output>100</output>

<gadget id="calculator">100 / 2</gadget>
<output>50</output>

<result>50</result>