I need help with this math problem for Algebra?

Question

Ok I have to find the missing values in the following sequences and write a rule for each. Giving me the answers directly is nice, but I need to know how to solve it.

a. 17, 12, 17, ___, 27, ___, ___, 42, ___, 52

Rule:

b. 5, 1, -3, ___, -11, -15, ___, ___, -27, ___

Rule:

c. -7, ___, -29, ___, -51, -62, ___, -84, ___

Rule:

d. 2, -4, -8 -16, 32, ___, 128, -256, ___, ___

Answer 1

a. 17, 12, 17, ___, 27, ___, ___, 42, ___, 52

if the first number was 7, then add 5 to the previous number to get

7, 12, 17, 22, 27, 32, 37, 42, 47, 52

b. 5, 1, -3, -7, -11, -15, -19, -23, -27, -31

subtract 4 from the previous number

c. -7, -18, -29, -40, -51, -62, -73, -84, -96

subtract 11 from the previous number

d. 2, -4, -8, -16, 32, __, 128, -256, __, __

if the -8 was +8, then multiply -2 times the previous number to get

2, -4, 8, -16, 32, -64, 128, -256, 512, -1024