A garment factory originally planned to process a batch of garments in 15 days. Since it processed 4 more garments per day than planned, the task was completed in 10 days. How many garments were originally planned to be processed per day?
一个服装厂原计划用15天加工一批服装，由于每天比计划多加工服装4件，结果10天就完成了任务，原计划每天加工服装多少件？
<gadget id="calculator">1 / 10</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">1 / 15</gadget>
<output>1/15 = around 0.066667</output>

<gadget id="calculator">(1/10) - (1/15)</gadget>
<output>1/30 = around 0.033333</output>

<gadget id="calculator">4 / (1/30)</gadget>
<output>120</output>

<gadget id="calculator">120 / 15</gadget>
<output>8</output>

<result>8</result>