Well No. 1 of a coal mine produces 961 tons of coal per day, which is twice the daily coal production of No. 2 well. No. 3 well produces 135.4 tons more coal per day than No. 2 well. The average daily coal production of these three wells is How many tons.
一个煤矿的一号井每日产煤961吨，是二号井每日产煤的吨数的2倍，三号井产煤每日比二号井多135.4吨，这三口井平均每口井日产煤多少吨．
<gadget id="calculator">961 / 2</gadget>
<output>961/2 = around 480.5</output>

<gadget id="calculator">(961/2) + 135.4</gadget>
<output>615.9</output>

<gadget id="calculator">961 + (961/2) + 615.9</gadget>
<output>2_057.4</output>

<gadget id="calculator">2_057.4 / 3</gadget>
<output>685.8</output>

<result>685.8</result>