The distance between A and B is 1200 meters. After Dacheng starts from A for 6 minutes, Xiaogong starts from B. After another 12 minutes, they meet each other. Dacheng walks 20 meters more than Xiaogong every minute, and Xiaogong walks every minute. How much rice.
A、B两地相距1200米，大成从A地出发6分钟后，小功从B地出发，又过了12分钟两人相遇，大成每分钟比小功多走20米，小功每分钟走多少米．
<gadget id="calculator">20 * 6</gadget>
<output>120</output>

<gadget id="calculator">20 * 12</gadget>
<output>240</output>

<gadget id="calculator">1_200 - 120 - 240</gadget>
<output>840</output>

<gadget id="calculator">6 + 12 + 12</gadget>
<output>30</output>

<gadget id="calculator">840 / 30</gadget>
<output>28</output>

<result>28</result>