Two teams, A and B, cooperate to build a 82km long canal. They construct the canal from opposite ends respectively. The repair is completed in 4 days. Team A repairs 8.5km every day. How many kilometers does Team B repair every day?
甲乙两队合作修一条长82km的水渠，分别从两端相向施工，4天修完，甲队每天修8.5km，乙队每天修多少千米？
<gadget id="calculator">82 / 4</gadget>
<output>41/2 = around 20.5</output>

<gadget id="calculator">(41/2) - 8.5</gadget>
<output>12</output>

<result>12</result>