Xiaojun collects 20 animal pictures and 4 landscape pictures, and gives 16 pictures to his classmates. How many pictures are left?
小军收集20张动物画片和4张风景画片，送给同学16张，还剩多少张．
<gadget id="calculator">4 - 16</gadget>
<output>-12</output>

<gadget id="calculator">20 + (-12)</gadget>
<output>8</output>

<result>8</result>