typist typed a manuscript, planned to finish it in 15 minutes, typed 200 characters per minute, actually typed 50 more characters per minute on average, how many minutes can the task be completed in advance?
打字员打一部稿件，计划15分钟完成，每分钟打200个字，实际平均每分钟多打50个字，可提前几分钟完成任务？
<gadget id="calculator">200 * 15</gadget>
<output>3_000</output>

<gadget id="calculator">200 + 50</gadget>
<output>250</output>

<gadget id="calculator">3_000 / 250</gadget>
<output>12</output>

<gadget id="calculator">15 - 12</gadget>
<output>3</output>

<result>3</result>