Alright, lets get started.
One report takes to file an average of = 45 minutes
Means 12 reports takes to file time = 12 * 45 = 540 minutes
12 reports filing total time = 540 minutes
We are asked to find time to file 75 % of them.
Which means 75 % of 540
= 540 * 75/100
= 540 * 0.75
= 405 minutes
We could convert it into hrs dividing with 60.
405 / 60 = 6.75 hrs
Means it will take 6.75 hrs to file 75% of them: Answer
Hope it will help :)