Master Zhang processes a batch of parts. The ratio of processed and unprocessed parts is 2:3. If 15 more parts are processed, 50% of this batch of parts can be completed. How many parts are there in total?
张师傅加工一批零件，已加工的和未加工的零件的比是2：3，如果再加工15个，就可以完成这批零件的50%，这批零件共有多少个？
<gadget id="calculator">50 / 100</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">2 + 3</gadget>
<output>5</output>

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

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

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

<result>150</result>