Mom bought a batch of eggs from the market at a price of 5 for 1 yuan, and then sold them at a price of 4 for 1 yuan. What is the profit margin on this sale of eggs, excluding losses?
妈妈从市场按1元钱5个的价钱进回一批鸡蛋，然后又按1元钱4个的价钱售出．若不计损耗，这次鸡蛋销售的利润率是多少？
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">(1/4) - (1/5)</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">(1/20) / (1/5)</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">100 / 100</gadget>
<output>1</output>

<gadget id="calculator">(1/4) * 1</gadget>
<output>1/4 = around 0.25</output>

<result>1/4 = around 0.25</result>