If a certain brand of color TV is sold at 20% off the list price, each set will lose 220 yuan; if it is sold at 10% off the list price, each set will make a profit of 200 yuan. How much is the purchase price of each color TV of this brand?
某品牌彩电，如果按标价八折出售，每台将亏本220元；如果按标价九折出售，每台将赢利200元．该种品牌彩电每台的进价是多少元？
<gadget id="calculator">220 + 200</gadget>
<output>420</output>

<gadget id="calculator">90 / 100</gadget>
<output>9/10 = around 0.9</output>

<gadget id="calculator">80 / 100</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>