To Find: m
Given: Sum of n terms, mth term
Put n = 1 to get the first term
So a1 = 3 + 5 = 8
Put n = 2 to get the sum of first and second term
So a1 + a2 = 12 + 10 = 22
So a2 = 14
Common difference = 14 – 8 = 6

Tn = a + (n – 1)d = 8 + (n – 1)6 = 6n + 2
Now 6m + 2 = 164
Or m = 27
The value of m is 27.