There are 28 children lined up in a row. The 10th from the left is Zhang Hua, what is his number from the right.
有28位小朋友排成一行．从左边开始数第10位是张华，从右边开始数他是第多少位．
<gadget id="calculator">28 - 10</gadget>
<output>18</output>

<gadget id="calculator">18 + 1</gadget>
<output>19</output>

<result>19</result>