The perimeter of a rectangular piece of paper is 80 cm, and the ratio of length to width is 5:3. If it is used to cut the largest square piece of paper, what is the area of this square piece of paper?
一个长方形纸片周长是80厘米，长和宽的比是5：3．如果用它剪成一个最大的正方形纸片，这个正方形纸片的面积是多少？
<gadget id="calculator">80 / 2</gadget>
<output>40</output>

<gadget id="calculator">5 + 3</gadget>
<output>8</output>

<gadget id="calculator">3 / 8</gadget>
<output>3/8 = around 0.375</output>

<gadget id="calculator">40 * (3/8)</gadget>
<output>15</output>

<gadget id="calculator">15 * 15</gadget>
<output>225</output>

<result>225</result>