Astudent is downloading his digital textbook. after 17 minutes, he's dismayed to find that there's still 81% of the download left. how long, to the nearest minute, is the total download?

The question has got numerous valuable information's that are required for getting to the desired answer. it is important to minutely read all the information's given in the question before going for solving.
It is already given in the qustion that after 17 minutes there is still 81% of the download reamining. This means that in 17 minutes the total download that took place is only 19%.
Based on this knowledge, the answer to the question can definitely be deduced.
So
The time taken for downloading 19 percent of the digital textbook = 17 minutes
Then
The time taken by the student for
 downloading 100 percent of the digital text book = (17/19) * 100 minutes
                                                                               = 1700/19 minutes
                                                                              = 89.47 minutes
So at this rate the student will need 89.47 minutes to complete the downloading of the digital text book.