What is the common difference in the sequence 9, 4, -1, -6?

a. 5

b. -5

c. 9

d. -11

(am i dividing or subtracting? )

for this case we must apply distributive property to the following expression:

the distributive property states that:

then, when applying the property we have to multiply the -2 for each term within the parenthesis:

i have not got your picture clearly so see it once again