A ticket for a ball game is 45 yuan a piece. After the price reduction, the audience will increase by 50%, and the income will increase by 25%. How much is the discount per ticket?
一场球赛的门票为45元一张，降价后观众增加50%，收入增加25%．每张门票降价多少元？
<gadget id="calculator">25 / 100</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 + (1/4)</gadget>
<output>5/4 = around 1.25</output>

<gadget id="calculator">50 / 100</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">(5/4) / (3/2)</gadget>
<output>5/6 = around 0.833333</output>

<gadget id="calculator">45 * 1 * (5/6)</gadget>
<output>75/2 = around 37.5</output>

<gadget id="calculator">45 - (75/2)</gadget>
<output>15/2 = around 7.5</output>

<result>15/2 = around 7.5</result>