1. a. 9, 11
b. 12, 14
c. 14, 17
d. 17, 15

e. -12, -17

2.
a.
b.
c.

3. a. 32, 64
b. 31, 63
c. 49, 97
d. 25, 36
e. 27, 38

4. a.  
b.

1
2
3
4
5
6
4
7
10
13
16
19

 

5. a. 9, 16, 25
b. 8, 12, 16, 20, 24
c. 28

6. a. F, S (Days of the week)
b. f, s (First letter of the numbers one, two, three etc.
c. 30, 31 (Number of days in months of year)
d. 13, 21 (Add previous two numbers in the sequence)
e. 13, 17 (Prime numbers)