To produce a batch of agricultural tools, the original plan was to produce 240 pieces per day, and it took 15 days to complete. In fact, 60 more pieces were produced per day. How many days were actually completed? (Solve with ratio)
生产一批农具，原计划每天生产240件，15天完成，实际每天多生产60件，实际多少天完成？(用比例解)
<gadget id="calculator">240 * 15</gadget>
<output>3_600</output>

<gadget id="calculator">240 + 60</gadget>
<output>300</output>

<gadget id="calculator">3_600 / 300</gadget>
<output>12</output>

<result>12</result>