The factory canteen used 13 tons of coal in the first quarter, (1/4) tons less in the second quarter than in the first quarter, and (3/5) more tons in the third quarter than in the second quarter. How many tons of coal was used in the third quarter ?
工厂食堂第一季度用煤13吨，第二季度比第一季度少用了(1/4)吨，第三季度比第二季度多用了(3/5)吨，第三季度用煤多少吨？
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">13 - (1/4)</gadget>
<output>51/4 = around 12.75</output>

<gadget id="calculator">3 / 5</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">(51/4) + (3/5)</gadget>
<output>267/20 = around 13.35</output>

<result>267/20 = around 13.35</result>