The naughty house used (2/5) tons of cement for decoration on the first day, and used (1/15) tons less on the second day than on the first day. How many tons of cement were used in the two days?
淘气家装修用水泥，第一天用去(2/5)吨，第二天比第一天少用了(1/15)吨，两天共用了多少吨水泥？
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 / 15</gadget>
<output>1/15 = around 0.066667</output>

<gadget id="calculator">(2/5) - (1/15)</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">(1/3) + (2/5)</gadget>
<output>11/15 = around 0.733333</output>

<result>11/15 = around 0.733333</result>