Master Zhou processed a batch of parts, 84 were processed on the first day, and the rest (2/7) were processed on the second day, which was just half of this batch of parts. How many parts are there in total? (solution by equation)
周师傅加工一批零件，第一天加工了84个，第二天加工了余下的(2/7)，刚好完成这批零件的一半．这批零件共有多少？(用方程解)
<gadget id="calculator">2 / 7</gadget>
<output>2/7 = around 0.285714</output>

<gadget id="calculator">84 * (2/7)</gadget>
<output>24</output>

<gadget id="calculator">84 - 24</gadget>
<output>60</output>

<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">(1/2) - (2/7)</gadget>
<output>3/14 = around 0.214286</output>

<gadget id="calculator">60 / (3/14)</gadget>
<output>280</output>

<result>280</result>