Answer:
17.0 %
Explanation:
% Gain = Difference/Original value × 100 %
Data:
September = 157 928 books
October = 184 211 books
Calculations:
Difference = October - September
= 184 211 - 157 928
= 26 913
% Difference = 26 913/157 928 × 100 %
= 17.0 %
The percent gain for October over September was 17.0 %.