Master Zhang processes a batch of parts. The ratio of the number of completed parts to the total number of parts on the first day is 1:3. If he processes 60 more parts, he can complete half of this batch of parts. How many parts are there in this batch?
张师傅加工一批零件，第一天完成的个数与零件总数的比是1：3，如果再加工60个，就可以完成这批零件的一半．这批零件共有多少个？
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">1 + 3</gadget>
<output>4</output>

<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">(1/2) - (1/4)</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">60 / (1/4)</gadget>
<output>240</output>

<result>240</result>