We have the next information
When he left the library he read 8/8-7/8= 1/8
then he read 1/10
after dinner, he read 2/5
First, we need to sum the fraction of the book he read
[tex]\frac{1}{8}+\frac{1}{10}+\frac{2}{5}[/tex]we need to have the same denominator in order to sum the fractions
[tex]\frac{5+4+16}{40}=\frac{25}{40}=\frac{5}{8}[/tex]the book complete represent 8/8 so we need to subtract 5/8 from the fraction of the complete book
[tex]\frac{8}{8}-\frac{5}{8}=\frac{3}{8}[/tex]the fraction of the book does he have left to read is 3/8
