The school cafeteria has (3/4) tons of coal, (1/3) is used in the first week, and (2/5) tons is used in the second week. How many tons of coal are used for two weeks and one week?
学校食堂有(3/4)吨煤，第一周用去(1/3)，第二周用去(2/5)吨．两周一共用去多少吨煤？
<gadget id="calculator">3 / 4</gadget>
<output>3/4 = around 0.75</output>

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

<gadget id="calculator">(3/4) * (1/3)</gadget>
<output>1/4 = around 0.25</output>

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

<gadget id="calculator">(1/4) + (2/5)</gadget>
<output>13/20 = around 0.65</output>

<result>13/20 = around 0.65</result>