If a commodity sells a certain kind of goods at a discount of 10% off the price, it can still make a profit of 20%. The purchase price of this kind of goods is 21 yuan per piece, so what is the price of each piece of goods?
一个商品把某种货物按标价的九折出售，仍可获利20%，该种货物的进价为每件21元，则每件货物的标价为多少
<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">90 / 100</gadget>
<output>9/10 = around 0.9</output>

<gadget id="calculator">(6/5) / (9/10)</gadget>
<output>4/3 = around 1.333333</output>

<gadget id="calculator">21 * (4/3)</gadget>
<output>28</output>

<result>28</result>