A section of steel is 4m long, and (3/20)m steel is used to make a part. 15 such parts have been made, how many m is left for this section of steel?
一段钢材长4m，做一个零件用(3/20)m的钢材，已经做了15个这样的零件，这段钢材还剩多少m？
<gadget id="calculator">3 / 20</gadget>
<output>3/20 = around 0.15</output>

<gadget id="calculator">(3/20) * 15</gadget>
<output>9/4 = around 2.25</output>

<gadget id="calculator">4 - (9/4)</gadget>
<output>7/4 = around 1.75</output>

<result>7/4 = around 1.75</result>