Only stuck on A not B

Identify a1 and r for the geometric sequence an= -256(-1/4) n-1

For the rule of 78, for a 12-month period, the last term in the sequence is 12 and the series sums to 78. for an 10 month period, the last term is and the series sum is . for a 15 month period, the last term is and the series sum is . for a 20 month period, the last term is and the series sum is

East black horse $0.25 total budget is $555 it'll cost $115 for other supplies about how many flyers do you think we can buy