It is question number 50. 69th is a part of it. I got the angular acceleration of pulley to be 2.5 rad/s^2. But I am not getting answer to 69th question which is given 12.5 rad/s (not even rad/s^2) in book. This is my only doubt. Thanks in advance!

 

As has been pointed out in your prior thread, you need to SHOW YOUR WORK.

We can't figure out if and/or where you are making a mistake unless you show your work.