college algebra word problem

Question

Find the first term or a₁ of an arithmetic sequence if a₆ = 12

 and a₁₄ = 28.

Answer 1

28-12 = 16

14-6 = 8

16/8 = 2 = common difference

6-1 = 5. 5x2 = 10

12-10 = 2 = a1

a1 through a6 =

2,4,6, 8, 10, 12

a6 through a14 =

12,14,16, 18,20,22,24,26,28