Assuming the first 5 terms are:
n = 0
n = 1
n = 2
n = 3
n = 4
a) 4n + 4
4(0) + 4 = 4
4(1) + 4 = 8
4(2) + 4 = 12
4(3) + 4 = 16
4(4) + 4 = 20
b) 8n + 3
8(0) + 3 = 3
8(1) + 3 = 11
8(2) + 3 = 19
8(3) + 3 = 27
8(4) + 3 = 35
c) 18 - 3n
18 - 3(0) = 18
18 - 3(1) = 15
18 - 3(2) = 12
18 - 3(3) = 9
18 - 3(4) = 6
