Which one set of letters when sequentially placed at the gaps in the given letter series shall complete it.

d_ _td_s_d_st

Direction: Study the following arrangement carefully and answer the given question below. 

S D 9 5 E # K 6 T I 8 P 1 % A 2 C λ L M U3 W @ N 4 © J $ 7 F B 

If all the symbols are dropped from the above arrangement, which of the following will be the 5th to the left of 12th element from right end?

If ’’624739854’’ 1 is added to all the even number and 1 is subtract from all the odd number, then what is the sum of the digits which is fifth from the left end and fourth from the right end?

In the word ‘BRISKLY’, how many pairs of the letters have the same number of letters between them in the word as in alphabet?

Directions: In each of the following questions, find out which of the letter series follows the given rule.
Number of letters skipped in between adjacent letters in the series is two. 

BDF, ? , PRT , WYA 

a_x_am_namxn_mx _

Directions: Study the following arrangement carefully and answer the questions given below—
1 R Z T 4 A 9 $ D F 1 U # B # 8 H I © X M H 3 2 P $ 5 N P 6 D

Which of the following is the fourth to the left of the twelfth from the left end?