The sports store originally had 20 footballs, 15 were shipped in, and 26 were sold, how many are left?
体育商店原来有20个足球，又运来15个，卖出26个，还剩多少个？
<gadget id="calculator">15 - 26</gadget>
<output>-11</output>

<gadget id="calculator">20 + (-11)</gadget>
<output>9</output>

<result>9</result>