Answer :
Let there are x number of pages in whole book. So 3/5 of a book is equal to 3/5x.
Determine the value of x.
[tex]\begin{gathered} \frac{3}{5}x=75 \\ x=75\cdot\frac{5}{3} \\ =125 \end{gathered}[/tex]So there are 125 pages in the whole book.