we know that
[tex] 86 [/tex] books represent the [tex] 100 [/tex]%
Find the percentage of [tex] 150 [/tex] books
by proportion
[tex] \frac{86}{100}\frac{books}{percentage} =\frac{150}{x} \frac{books}{percentage} \\\\ 86*x=150*100 [/tex]
[tex] x= 174.42 [/tex]%
Find the percentage increase
Percentage increase=[tex] 174.42-100=74.42 [/tex]%
therefore
the answer is
The percentage increase is [tex] 74.42 [/tex]%