Watching an episode of "Animation World", it takes (1/10) hours for the beginning and end of the credits, and (1/8) hours for commercials in the middle. It is known that the total broadcast time of each episode is (3/4) hours. How many hours is it on air?
看一集《动画世界》，片头和片尾用了(1/10)小时，中间插播广告用(1/8)小时，已知每集一共播出时间为(3/4)小时，每集实际播出时间是多少小时？
<gadget id="calculator">3 / 4</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">1 / 10</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">1 / 8</gadget>
<output>1/8 = around 0.125</output>

<gadget id="calculator">(3/4) - (1/10) - (1/8)</gadget>
<output>21/40 = around 0.525</output>

<result>21/40 = around 0.525</result>