The profit rate of a commodity is 20%. If the purchase price is reduced by 20% and the selling price remains the same, how much will the profit rate increase?
某商品的利润率是20%，如果进货价降低20%，售出价保持不变，那么利润率将要提高多少．
<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 + (1/5)</gadget>
<output>6/5 = around 1.2</output>

<gadget id="calculator">1 * (6/5)</gadget>
<output>6/5 = around 1.2</output>

<gadget id="calculator">1 - (1/5)</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">1 * (4/5)</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">(6/5) - (4/5)</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">(6/5) - 1</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">(2/5) - (1/5)</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">(1/5) / (1/5)</gadget>
<output>1</output>

<result>1</result>