Pl help me with the method of solving such questions and how to know whether they are in series or parallel ? In the above image

Hiii Kunde,

As shown in the figure the metallic plates are kept one above the other, The distance between the plates is d. 

 you should  take this plate in parallel, because the plates are placed one above the other, There will be three capacitance formed in parallel , and solve the question accordingly .

Hope this will help.