The price of each piece of a certain commodity is 550 yuan, and when it is sold at 20% off the price, it can still make a profit of 10%. What is the purchase price of each piece of this commodity?
某种商品每件的标价是550元，按标价的八折销售时，仍可获利10%，则这种商品每件的进价为多少．
<gadget id="calculator">1 + 0.1</gadget>
<output>1.1</output>

<gadget id="calculator">440 / 1.1</gadget>
<output>400</output>

<result>400</result>