A ticket for a football game is 15 yuan. After the price reduction, the audience increases by half, and the income increases by one-fifth. How much is the price reduction for a ticket?
足球赛门票15元一张，降价后观众增加了一半，收入增加了五分之一，一张门票降价是多少元．
<gadget id="calculator">1 / 5</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">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">1 + (1/2)</gadget>
<output>3/2 = around 1.5</output>

<gadget id="calculator">(6/5) / (3/2)</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">15 * (4/5)</gadget>
<output>12</output>

<gadget id="calculator">15 - 12</gadget>
<output>3</output>

<result>3</result>