The garment factory produced a batch of school uniforms. It was originally planned to be completed in 15 days, but it actually produced 30 more sets per day than planned. Therefore, it was completed 3 days earlier than planned. How many sets of this batch of school uniforms are there?
服装厂生产一批校服，原计划15天完成，实际每天比计划多做30套，因此比计划提前3天完成，这批服校服共有多少套？
<gadget id="calculator">15 - 3</gadget>
<output>12</output>

<gadget id="calculator">12 / 3</gadget>
<output>4</output>

<gadget id="calculator">30 * 4 * 15</gadget>
<output>1_800</output>

<result>1_800</result>