The production of plastic boxes in the school-run factory has completed 85% of the original plan. If 3,000 more are produced, it will exceed 15% of the plan. How many were originally planned?
校办厂生产塑料盒，已经完成原计划的85%，如果再生产3000个，就超过计划15%，原计划生产多少个？
<gadget id="calculator">15 / 100</gadget>
<output>3/20 = around 0.15</output>

<gadget id="calculator">85 / 100</gadget>
<output>17/20 = around 0.85</output>

<gadget id="calculator">(3/20) - (17/20)</gadget>
<output>-7/10 = around -0.7</output>

<gadget id="calculator">1 + (-7/10)</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">3_000 / (3/10)</gadget>
<output>10_000</output>

<result>10_000</result>