As 5 31 159 645 1951 3927 
5x6+1 = 31 
31x5+4 =159 
159x4+9 = 645 
 645x3+16 = 1951 
1951x2+25 = 3927 
Same as (A)  (B)  (C)  (D)  (E)              3 19    99 405 1231 2487 
3x6+1 = 19 
19x5+4 = 99 
99x4+9 = 405 
405x3+16 = 1231 
1231x2+25 = 2487
Hence in place of (B) number 99 will be come

As 7 13 31 97 391 1957 
Here 7x1+6 = 13 
13x2+5 = 31 
31x3+4 = 97 
97x4+3= 391 
391x5+2 = 1957 
     (A)   (B)   (C)   (D)  (E) 13 19    43   133  535 2677 
Same as 13x1+6 =19 
19x2+5 = 43 
43x3+4= 133 
133x4+3 = 535 
535x5+2 = 2677 
Hence in place of (D) number 535 will be come.

As 8 7 12 33 128 635 
Here 8x1-1 =7 
7x2-2 = 12 
12x3-3 = 33 
33x4-4 =128 
128x5-5 = 635 
          (A) (B)  (C)  (D)  (E) 
Now 6 5     8   21   80   395 
6x1-1 = 5 
5x2-2 = 8 
8x3-3 = 21 
21x4-4 =80 
80x5-5 = 395 
Hence in place of (C) number 21 will come.

This is an alternating addition series, with a random number, 35, interpolated as every
third number. The pattern of addition is to
add 2, add 5, add 2, and so on. The number
35 comes after each "add 2 step.

This is an alternating subtraction series,
which subtracts 5, then 2, then 5, and so on.

Here, every third number follows a different
pattern from the main series. In the main
series, beginning with 16, 10 is added to
each number to arrive at the next. In the
alternating series, beginning with 56, 12 is
added to each number to arrive at the next.

Here, there are two alternating patterns,
with every other number following a different pattern. The first pattern begins with 13 and adds 2 to each number to arrive at the next; the alternating pattern begins with 29 and subtracts 3 each time.

This is an alternating addition series with
repetition, in which a random number, 66,
is interpolated as every third number. The
regular series adds 2, then 3, then 2, and so on, with 66 repeated after each "add 2 step.

.

R1 = 40  30  3600                                Now R2=1524  17
   =(40x30)3600                                                    =(15+27)     17
   =1200                                                        =39 17
   =(3600/1200) = 3                                      = 39 -17 = 22
Required sun =R1+R2 = 22+3 =25.