There are 10 sheep on the grass, 3 white goats ran away, and 7 black goats came again, how many sheep are there now?
草地上有10只羊，跑走了3只白山羊，又来了7只黑山羊，现在共有几只羊？
<gadget id="calculator">10 - 3</gadget>
<output>7</output>

<gadget id="calculator">7 + 7</gadget>
<output>14</output>

<result>14</result>