cement factory planned to produce a batch of cement in January, but actually completed the plan (1/3) in the first ten days, completed the planned (2/5) in the middle ten days, and produced another 260,000 tons in the second ten days, and overfulfilled the plan (1/5) 6). How many tons of cement does the cement plant plan to produce in January?
某水泥厂一月份计划生产一批水泥，实际上旬完成了计划的(1/3)，中旬完成了计划的(2/5)，下旬又生产了26万吨，结果超额完成计划的(1/6)．水泥厂一月份计划生产水泥多少吨？
<gadget id="calculator">1 / 6</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">(1/6) - (1/3) - (2/5)</gadget>
<output>-17/30 = around -0.566667</output>

<gadget id="calculator">1 + (-17/30)</gadget>
<output>13/30 = around 0.433333</output>

<gadget id="calculator">26 / (13/30)</gadget>
<output>60</output>

<result>60</result>