find answer for the following

please find the answer.
a+3d=18 ----(i)
and,
(a+8d)-(a+14d) = 30
a+8d-a-14d=30
6d=30
d=30/6
d=5
substituting d=5 in eq.(i)
a+3×5=18
a+15=18
a=18-15
a=3
A.P.=a,a+d,a+2d.......
=3,3+5,3+10.....
=3,8,13....

hope this helps.