28 children are lined up, counting from left to right, Zhang Hua is the 10th, and Li Ming is on the left of Zhang Hua, then counting from right to left, what is the number of Li Ming?
28位小朋友排成一行，从左向右数，第10位是张华，张华左边的左边是李明，那么从右向左数，李明是第多少位．
<gadget id="calculator">10 - 1 - 2</gadget>
<output>7</output>

<gadget id="calculator">28 - 7</gadget>
<output>21</output>

<result>21</result>