Master Li wants to process a batch of parts. He processed (3/10) on the first day and processed (2/5) on the second day. How many parts are left unprocessed?
李师傅要加工一批零件，第一天加工了(3/10)，第二天加工了(2/5)，还剩多少没有加工？
<gadget id="calculator">3 / 10</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

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

<result>3/10 = around 0.3</result>