ANSWER
[tex]a_ {n} =a_ {n - 1} + 8, \: \: a_1=20[/tex]
EXPLANATION
The given sequence is:
[tex]20,28,36,44,...[/tex]
The first term is
[tex]a_1=20[/tex]
The constant difference is
[tex]d = 28 - 20[/tex]
[tex]d = 8[/tex]
The nth term of the sequence is given by the recursive formula,
[tex]a_ {n} =a_ {n - 1} + 8, \: \: a_1=20[/tex]
