Answer: 60 pages left.
Step-by-step explanation:
Let the number of pages in the book be x.
As per given, we have
[tex]\dfrac14x+20=\dfrac13x\\\\\Rightarrow\ \dfrac{1}{3}x-\dfrac14 x=20\\\\\Rightarrow\ \dfrac{4-3}{12}x=20\\\\\Rightarrow\ \dfrac1{12}x=20\\\\\Rightarrow x=20\times12\\\\\Rightarrow x=240[/tex]
[tex]\dfrac34[/tex] of total book = [tex]\dfrac34\times 240=180[/tex]
Pages left = 240-180
= 60
Hence, 60 pages left.
