If a commodity is sold at a 10% discount to the current price, the profit will be 200 yuan. If it is sold at a 20% discount to the current price, the loss will be 220 yuan. What is the purchase price of this commodity?
有一种商品如果按现价降低10%出售，盈利200元，如果按现价降低20%出售后，则亏损220元，这种商品的进价是多少元？
<gadget id="calculator">200 + 220</gadget>
<output>420</output>

<gadget id="calculator">10 / 100</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">1 - (1/10)</gadget>
<output>9/10 = around 0.9</output>

<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

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

<gadget id="calculator">(9/10) - (4/5)</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">420 / (1/10)</gadget>
<output>4_200</output>

<gadget id="calculator">4_200 * (4/5)</gadget>
<output>3_360</output>

<gadget id="calculator">3_360 + 220</gadget>
<output>3_580</output>

<result>3_580</result>