Answer:
4 + 12 + 36 + ...
Step-by-step explanation:
4, 12, 36, ... is a geometric sequence, it has a common ratio of 
When we add the terms of a geometric sequence we get a geometric series.
4+12+36+ ... is a geometric series, it has a common ratio of 
4 + 12 + 20 + ... is not a geometric series because it has no common ratio

The second choice is correct
Answer:
1,231 people
Step-by-step explanation:
1,256 people currently subscribe. $0.25 is 5 nickels, and for every nickel the price is raised, 5 people unsubscribe. That's 1 person per cent. 25 people will unsubscribe for every $0.25 the price is raised. 1,256-25 is 1,231, so 1,231 people will continue to subscribe after the price increase.
3 (k-12) = k-30
3k - 36 = k - 30
3k - k = -30 + 36
2k = 6
k = 3