The cost of two commodities, A and B, is 400 yuan. Commodity A is priced at a profit of 30%, and commodity B is priced at a profit of 20%. Later, both commodities are sold at a discount of 10% of the price, and the result is a profit of 55 yuan. How much does it cost?
甲、乙两种商品成本共400元，甲商品按30%的利润定价，乙商品按20%的利润定价，后来两种商品都按定价打九折出售，结果还获利55元，甲商品的成本是多少元？
<gadget id="calculator">90 / 100</gadget>
<output>9/10 = around 0.9</output>

<gadget id="calculator">400 * (9/10)</gadget>
<output>360</output>

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

<gadget id="calculator">400 * (1/5) * (9/10)</gadget>
<output>72</output>

<gadget id="calculator">55 - 360 - 72</gadget>
<output>-377</output>

<gadget id="calculator">400 + (-377)</gadget>
<output>23</output>

<gadget id="calculator">30 / 100</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">(3/10) * (9/10)</gadget>
<output>27/100 = around 0.27</output>

<gadget id="calculator">(1/5) * (9/10)</gadget>
<output>9/50 = around 0.18</output>

<gadget id="calculator">(27/100) - (9/10) - (9/50)</gadget>
<output>-81/100 = around -0.81</output>

<gadget id="calculator">(9/10) + (-81/100)</gadget>
<output>9/100 = around 0.09</output>

<gadget id="calculator">23 / (9/100)</gadget>
<output>2_300/9 = around 255.555556</output>

<result>2_300/9 = around 255.555556</result>