piece of steel is 12 meters long. The first time uses up 1/4 of the full length, and the second time uses 40% of the full length. How much more meters are used in the second time than in the first time?
一段钢材长12米，第一次用去全长的(1/4)，第二次用去全长的40%，第二次比第一次多用去多少米？
<gadget id="calculator">40 / 100</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

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

<gadget id="calculator">12 * (3/20)</gadget>
<output>9/5 = around 1.8</output>

<result>9/5 = around 1.8</result>