a) your iterative rule would be: 22,28,34,40....... it is because there are 22 in first row and it is increasing by 6 at each step....
b) Now, a(n) = 100, a=22, d=28-22 = 6
we know, a(n) = a+(n-1)d
100 = 22+(n-1)6
100-22 = 6n-6
78+6 = 6n
n = 84/6
n= 14
