There is a square iron block with a side length of 3 decimeters. Now it is forged into a cuboid. The cross section of this cuboid is a rectangle with a length of 20 cm and a width of 15 cm. Find its length.
有一块边长3分米的正方形铁块，现把它锻造成一个长方体，这个长方体的截面是一个长20厘米，宽15厘米的长方形，求它的长．
<gadget id="calculator">20 * 15</gadget>
<output>300</output>

<gadget id="calculator">1_000 / 300</gadget>
<output>10/3 = around 3.333333</output>

<gadget id="calculator">3 * 3 * 3 * (10/3)</gadget>
<output>90</output>

<result>90</result>