If 3 squares with a side length of 15 cm are put together to form a rectangle, the perimeter of this rectangle is reduced by how many centimeters compared to the sum of the perimeters of the original three squares.
边长是15厘米的3个正方形拼成一个长方形，这个长方形的周长和原来三个正方形的周长和相比，减少多少厘米．
<gadget id="calculator">15 * 4</gadget>
<output>60</output>

<result>60</result>