Tickets for the chrysanthemum exhibition are 10 yuan each. After the price reduction, the number of visitors doubled and the income increased by 20%. How much is the price of a ticket reduced?
菊花展门票每张10元，降价后参观人数是原来的2倍，收入增加了20%，一张门票降价了多少元．
<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">100 / 100</gadget>
<output>1</output>

<gadget id="calculator">1 + 1</gadget>
<output>2</output>

<gadget id="calculator">(6/5) / 2</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">1 - (3/5)</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">10 * (2/5)</gadget>
<output>4</output>

<result>4</result>