15 boxes of products, 20 products in each box, after inspection, the pass rate is 95%. How many defective products are there?
15箱产品，每箱20件产品，经检验，合格率是95%．有多少件次品．
<gadget id="calculator">20 * 15</gadget>
<output>300</output>

<gadget id="calculator">95 / 100</gadget>
<output>19/20 = around 0.95</output>

<gadget id="calculator">20 * 15 * (19/20)</gadget>
<output>285</output>

<gadget id="calculator">300 - 285</gadget>
<output>15</output>

<result>15</result>