To find the number of missing pages:
[tex]\frac{1}{2}-\frac{1}{5}=[/tex]rewriting the expression as homogeneous fractions:
[tex]\frac{1}{2}\times\frac{5}{5}-\frac{1}{5}\times\frac{2}{2}=[/tex]simplifying it:
[tex]\frac{5}{10}-\frac{2}{10}=\frac{3}{10}[/tex]ANSWER
you have left 3/10 page.