20 children line up, counting from the left, Xiao Hua is the 11th, and counting from the right, which one is Xiao Hua?
20个小朋友排队，从左边数小花是第11个，从右边数小花是第几个？
<gadget id="calculator">20 - 11</gadget>
<output>9</output>

<gadget id="calculator">9 + 1</gadget>
<output>10</output>

<result>10</result>