A factory plans to produce 240 machine tools in 15 days, but actually produces 4 more machines per day than planned. How many days does it actually take?
一个工厂计划15天生产240台机床，实际每天比计划多生产4台，实际需几天完成？
<gadget id="calculator">240 / 15</gadget>
<output>16</output>

<gadget id="calculator">16 + 4</gadget>
<output>20</output>

<gadget id="calculator">240 / 20</gadget>
<output>12</output>

<result>12</result>