5x-3 The terms of an infinite geometric series are given by a = 4(0.75)* 22 Show all work to find: a) the first term of the series. b) the common ratio of the series, rounded to four decimal places if necessary. c) the sum of the series, rounded to the nearest hundredth if necessary.

1) Determine the sum of the arithmetic series when t1 = -6, d = 4, and n = 50. step-by-step answer 2)  How many terms of the arithmetic sequence 15, 12, 9, … must be added together to get a sum of -39? step-by-step answer.