Verify value in text file

Good day 

I need to verify a specific value in a text file. It's a date value in YY/MM/DD format. It's in line 3 and starts at column 59 and ends at column 64.

From what I can see in the tutorials you can only compare files byte for byte . I want to verify if the date in the file , in line 3 between , column 59 and 64 is current date + 2 days. So the date in the file must be two days from today's date . I need to verify this specifically. 

Can someone perhaps help ?

Thank you