Master Li processes a batch of parts. The ratio of the number of completed parts to the total number of parts on the first day is 2:5. If 15 more parts are processed, the remaining parts will be as many as the ones processed. How many parts are there in total?
李师傅加工一批零件，第一天完成的个数与零件总数的比是2：5，如果再加工15个，剩下的个数和已加工的就一样多．这批零件一共多少个？
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 - (2/5)</gadget>
<output>3/5 = around 0.6</output>

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

<gadget id="calculator">(3/5) - (1/2)</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">15 / (1/10)</gadget>
<output>150</output>

<result>150</result>