Use several computers to enter a book at the same time, and plan to complete it in several hours. If you add 3 computers, you only need 75% of the original time; if you reduce 3 computers, you will use (5/6) hours more than the original time. So how many hours is the original time to complete the entry of this manuscript?
用若干台计算机同时录入一部书，计划若干小时完成，如果增加3台计算机，则只需原定时间的75%；如果减少3台计算机，则比原定时间多用(5/6)小时，那么原定完成录入这部书稿的时间是多少小时．
<gadget id="calculator">5 / 6</gadget>
<output>5/6 = around 0.833333</output>

<gadget id="calculator">75 / 100</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">1 / (3/4)</gadget>
<output>4/3 = around 1.333333</output>

<gadget id="calculator">(4/3) - 1</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">3 / (1/3)</gadget>
<output>9</output>

<gadget id="calculator">1 / 9</gadget>
<output>1/9 = around 0.111111</output>

<gadget id="calculator">9 - 3</gadget>
<output>6</output>

<gadget id="calculator">1 / 6</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">(1/6) - (1/9)</gadget>
<output>1/18 = around 0.055556</output>

<gadget id="calculator">(1/9) / (1/18)</gadget>
<output>2</output>

<gadget id="calculator">(5/6) * 2</gadget>
<output>5/3 = around 1.666667</output>

<result>5/3 = around 1.666667</result>