It takes (2/5) hours for Mr. Wang to produce a part, which is (7/25) hours less than in the past. How many hours did it take to produce a part in the past?
王师傅生产一种零件，现在生产一个需要(2/5)小时，比过去节约(7/25)小时．过去生产一个零件的时间是多少小时？
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">7 / 25</gadget>
<output>7/25 = around 0.28</output>

<gadget id="calculator">(2/5) + (7/25)</gadget>
<output>17/25 = around 0.68</output>

<result>17/25 = around 0.68</result>