The sum of number A is 29, and the sum of number B is 18. When A and B are added vertically, there will be a three-digit carry. What is the sum of these two numbers?
甲数数字和是29，乙数数字和是18，当甲、乙两数用竖式相加时，有三位进位，那么这两数和的数字和是多少．
<gadget id="calculator">9 * 3</gadget>
<output>27</output>

<gadget id="calculator">18 - 27</gadget>
<output>-9</output>

<gadget id="calculator">29 + (-9)</gadget>
<output>20</output>

<result>20</result>