pool can hold 84 tons of water, and there are two water injection pipes for water injection. The pool can be filled in 8 hours by opening the A pipe alone, and it can be filled in 6 hours by opening the B pipe alone. Now open the two water pipes at the same time. When the pool is filled, how many tons of water will the second pipe inject into the pool?
一个水池可容水84吨，有两个注水管注水，单开甲管8小时可将水池注满，单开乙管6小时可注满．现在同时打开两个水管，注满水池时，乙管注入水池多少吨水？
<gadget id="calculator">3 + 4</gadget>
<output>7</output>

<gadget id="calculator">4 / 7</gadget>
<output>4/7 = around 0.571429</output>

<gadget id="calculator">84 * (4/7)</gadget>
<output>48</output>

<result>48</result>