For a piece of clothing, if the price is reduced by 30%, you will lose 30 yuan. If the price is increased by 30%, you will make a profit of 90 yuan. What is the cost of this piece of clothing?
一件衣服，如果降价30%，就亏了30元，如果涨价30%，那么会赚90元，这件衣服的成本是多少元．
<gadget id="calculator">30 + 90</gadget>
<output>120</output>

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

<gadget id="calculator">(3/10) - 1</gadget>
<output>-7/10 = around -0.7</output>

<gadget id="calculator">(3/10) + 1 + (-7/10)</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">120 / (3/5)</gadget>
<output>200</output>

<result>200</result>