The third level has 80 books because 64 / .8 = <<64/.8=80>>80
The second level has 100 books because 80 / .8 = <<80/.8=100>>100
The first level has 125 books because 100 / .8 = <<100/.8=125>>125
In total there are 369 books because 64 + 80 + 100 + 125 = <<64+80+100+125=369>>369
#### 369