Xiaowei spent (2/5) hours on Chinese homework, which was (2/15) hours more than Xiaogang, and Xiaohua took (1/4) hours more than Xiaogang, Xiaohua and Xiaowei, who used it not much time? How much less?
小伟做语文作业用了(2/5)小时，比小刚多用了(2/15)小时，小华比小刚多用了(1/4)小时，小华和小伟比，谁用的时间少？少多少？
<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">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">(1/4) - (2/5)</gadget>
<output>-3/20 = around -0.15</output>

<gadget id="calculator">(4/15) + (-3/20)</gadget>
<output>7/60 = around 0.116667</output>

<result>7/60 = around 0.116667</result>