A worker processes a batch of machine parts, and (7/15) of this batch of parts is completed on the first day, and (1/15) of this batch of parts is completed on the second day, what fraction of this batch of parts is completed on the second day?
工人加工一批机器零件，第一天完成这批零件的(7/15)，比第二天多完成这批零件的(1/15)，第二天完成这批零件的几分之几？
<gadget id="calculator">7 / 15</gadget>
<output>7/15 = around 0.466667</output>

<gadget id="calculator">1 / 15</gadget>
<output>1/15 = around 0.066667</output>

<gadget id="calculator">(7/15) - (1/15)</gadget>
<output>2/5 = around 0.4</output>

<result>2/5 = around 0.4</result>