Costing is a pain

I have also undergone pains like you but what i feel is nowadays as students you have lot of resources and at that time when we are doing our c.A there are no such resouces like the internet nor a book like padhukas .I sincerely suggest to read padhuka for entire gamat of the theory for all chapters and practice problems because it covers rtp,Modules and Compiler Questions.All the very best for the coming attempt

agreed wid shiva ram

paduka is the answer of your question