(i) 3, 8, 13...
Here, we have:
a = 3
Hence, 248 is the 50th term of the given A.P.
(ii) 84, 80, 76...
Here, we have:
a = 84
Hence, 0 is the 22nd term of the given A.P.
(iii) 4, 9, 14...
Here, we have:
a = 4
Hence, 254 is the 51st term of the given A.P.