Answer :
500 + 10n = 15,000
Subtract 500 from each side:
10n = 14,500
Divide each side by 10 :
n = 1,450 books
Subtract 500 from each side:
10n = 14,500
Divide each side by 10 :
n = 1,450 books
[tex]500+10n=15.000 \\ \\ 500-500+10n =15.000-500 \\ \\ 10n=14.500 \\ \\ n= \frac{14.500}{10} \\ \\ \boxed{n=1.450}[/tex]