Two engineering teams, A and B, dig a 480-kilometer-long tunnel from both ends at the same time, and plan to complete it in 30 days. Team A completes 7 kilometers per day, how many kilometers per day does Team B complete? (solution by equation)
甲、乙两个工程队同时从两端开凿一条长480千米的隧道，计划30天完成．甲队每天完成7千米，乙队每天完成多少千米？(用方程解)
<gadget id="calculator">7 * 30</gadget>
<output>210</output>

<gadget id="calculator">480 - 210</gadget>
<output>270</output>

<gadget id="calculator">270 / 30</gadget>
<output>9</output>

<result>9</result>