Answer: 745
Step-by-step explanation: if there were initialy 80 books and its increasing by 25% every month, for month 1 we have:
25% = 0,25
increase is 1+0.25
M1 = 80.(1+0.25)¹ = 80.1.25 = 100
M10 = 80 (1+0.25)¹⁰ = 80. 9.313225 = 745.05 (end of the month)