A section of steel is 21m long, and it takes (6/5)m to make a part. 10 such parts have been made, how many meters are left in this section of steel?
一段钢材长21m，做一个零件用(6/5)m，已经做了10个这样的零件，这段钢材还剩下多少米？
<gadget id="calculator">6 / 5</gadget>
<output>6/5 = around 1.2</output>

<gadget id="calculator">(6/5) * 10</gadget>
<output>12</output>

<gadget id="calculator">21 - 12</gadget>
<output>9</output>

<result>9</result>