To finish an audiobook 30 hours long, listening to 2 hours of each audiobook a day, Fernanda took 30 hours / 2 hours/day =<<30/2=15>>15 days to finish one audiobook.
If she purchased 6 audiobooks, the total number of days she will take to finish all the audiobooks is 6 audiobooks * 15 days/audiobook = <<6*15=90>>90 days
#### 90