For an 80-meter-long water pipe, 25% of the total length was used for the first time, and more (2/5) was used for the second time than the first time. How many meters are left to be useless after the two times?
一根80米长的水管，第一次用了全长的25%，第二次比第一次多用了(2/5)，两次后还剩多少米没有用？
<gadget id="calculator">25 / 100</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">80 * (1/4)</gadget>
<output>20</output>

<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 + (2/5)</gadget>
<output>7/5 = around 1.4</output>

<gadget id="calculator">20 * (7/5)</gadget>
<output>28</output>

<gadget id="calculator">80 - 20 - 28</gadget>
<output>32</output>

<result>32</result>