A triangular drape used in the hospital is an isosceles right-angled triangle, and the length of the right angle is 4 decimeters. Now there is a rectangular white cloth with a length of 20 decimeters and a width of 12 decimeters. How many pieces of this triangular drape can be cut at most?
医院用的一种三角巾是等腰直角三角形，直角边长4分米，现在有一块长20分米，宽12分米的长方形白布，最多可以剪出多少块这样的三角巾？
<gadget id="calculator">12 / 4</gadget>
<output>3</output>

<result>3</result>