A manuscript can be completed in 5 hours by A alone, 3 hours by A and B together, how many hours can B complete it alone?
一份稿件，甲独打5小时完成，甲乙合打3小时完成，乙独打几小时完成？
<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">(1/3) - (1/5)</gadget>
<output>2/15 = around 0.133333</output>

<gadget id="calculator">1 / (2/15)</gadget>
<output>15/2 = around 7.5</output>

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