The construction site has a total of 40 tons of cement, which was used up (2/5) in the first week, and (3/4) of the first week was used up in the second week. How many tons are used in the second week?
建筑工地一共有40吨水泥，第一周用去了(2/5)，第二周用去的是第一周的(3/4)．第二周用去多少吨？
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">3 / 4</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">40 * (2/5) * (3/4)</gadget>
<output>12</output>

<result>12</result>