A coat is priced at a profit of 40%, and it is actually sold at a discount of 20%, which makes a profit of 90 yuan. What is the cost price of this coat?
一件大衣按40%的利润定价，实际打八折出售，这样还获利90元，这件大衣的成本价是多少元？
<gadget id="calculator">40 / 100</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 + (2/5)</gadget>
<output>7/5 = around 1.4</output>

<gadget id="calculator">80 / 100</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">1 * (7/5) * (4/5)</gadget>
<output>28/25 = around 1.12</output>

<gadget id="calculator">(28/25) - 1</gadget>
<output>3/25 = around 0.12</output>

<gadget id="calculator">90 / (3/25)</gadget>
<output>750</output>

<result>750</result>