On a certain Sunday, Xiaowei spent (2/5) hours on Chinese homework, and (2/15) hours less on math homework than on Chinese homework. How many hours did he spend on Chinese homework and math homework?
某星期日，小伟做语文作业用了(2/5)小时，做数学作业比做语文作业少用了(2/15)小时．他做语文作业和数学作业一共用了多少小时？
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">2 / 15</gadget>
<output>2/15 = around 0.133333</output>

<gadget id="calculator">(2/5) - (2/15)</gadget>
<output>4/15 = around 0.266667</output>

<gadget id="calculator">(4/15) + (2/5)</gadget>
<output>2/3 = around 0.666667</output>

<result>2/3 = around 0.666667</result>