Xiaohong first formed an equilateral triangle with all the five-cent coins that she usually saved, which was just used up, and then changed into a square, which was just used up. Each side of a square costs 5 coins less than each side of a triangle. How much is Xiaohong's five-cent coin worth?
小红把平时节省下来的全部五分硬币先围成一个正三角形，正好用完，后来又改围成一个正方形，也正好用完．正方形每条边比三角形每条边少用5枚硬币．小红的五分硬币共价值多少元．
<gadget id="calculator">4 * 5</gadget>
<output>20</output>

<gadget id="calculator">4 - 3</gadget>
<output>1</output>

<gadget id="calculator">20 + 1</gadget>
<output>21</output>

<gadget id="calculator">21 / 1</gadget>
<output>21</output>

<gadget id="calculator">3 * 21</gadget>
<output>63</output>

<gadget id="calculator">63 - 3</gadget>
<output>60</output>

<gadget id="calculator">5 / 100</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">60 * (1/20)</gadget>
<output>3</output>

<result>3</result>