A rope is 4 meters long, (2/5) meter is used for the first time, and the remaining 90% is used for the second time, how many meters is used for the second time?
一根绳子长4米，第一次用去(2/5)米，第二次用去剩下的90%，第二次用去多少米？
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">4 - (2/5)</gadget>
<output>18/5 = around 3.6</output>

<gadget id="calculator">90 / 100</gadget>
<output>9/10 = around 0.9</output>

<gadget id="calculator">(18/5) * (9/10)</gadget>
<output>81/25 = around 3.24</output>

<result>81/25 = around 3.24</result>