wire uses 40% of the total length for the first time, and uses up 3/10 of the total length for the second time. The first time uses 4.5 meters more than the second time. How many meters is left for this wire?
一根电线第一次用去全长的40%，第二次用去全长的(3/10)，第一次比第二次多用4.5米，这根电线还剩多少米？
<gadget id="calculator">40 / 100</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">3 / 10</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">(2/5) - (3/10)</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">4.5 / (1/10)</gadget>
<output>45</output>

<gadget id="calculator">1 - (2/5) - (3/10)</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">45 * (3/10)</gadget>
<output>27/2 = around 13.5</output>

<result>27/2 = around 13.5</result>