The bus stopped, 8 people went down, and 3 people came up, now there are 24 people in the bus. How many people were there in the bus?
公共汽车靠站了，下去8人，又上来3人，现在公共汽车里共有24人．公共汽车里原来有多少人？
<gadget id="calculator">24 - 3</gadget>
<output>21</output>

<gadget id="calculator">21 + 8</gadget>
<output>29</output>

<result>29</result>