A workshop plans to process a batch of parts. If it processes 60 parts per day, it will be completed 1 day later than planned. If it processes 75 parts per day, it will be completed 1 day earlier than planned. How many parts are there in this batch?
某车间计划加工一批零件，如果每天加工60个零件，则比计划推迟1天完成，如果每天加工75个零件，则比计划提前1天完成，这批零件共有多少个？
<gadget id="calculator">60 * 1</gadget>
<output>60</output>

<gadget id="calculator">75 * 1</gadget>
<output>75</output>

<gadget id="calculator">60 + 75</gadget>
<output>135</output>

<gadget id="calculator">75 - 60</gadget>
<output>15</output>

<gadget id="calculator">135 / 15</gadget>
<output>9</output>

<gadget id="calculator">9 * 60</gadget>
<output>540</output>

<gadget id="calculator">540 + 60</gadget>
<output>600</output>

<result>600</result>