For a manuscript, A can finish copying in 10 hours alone, and B can finish copying in 12 hours alone. Now A and B will copy together for 2 hours, and (3/4) of this manuscript is finished, and there are still 20 pages left. How many pages does this manuscript have?
一份稿件，甲独抄10小时抄完，乙独抄12小时抄完．现在由甲、乙两人合抄2小时，抄完这份稿件的(3/4)，还差20页，这份稿件有多少页？
<gadget id="calculator">3 / 4</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">1 - (3/4)</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">20 / (1/4)</gadget>
<output>80</output>

<result>80</result>