Find the 7th term of arithmetic progression...12,20,28.

Answer 1

a= 12
d = 8
n = 7
Sn 1/2n[(2a+ (n-1)d)]

7/2[(2*12+ (7-1)8)]
7/2(24+48)

Sn = 7/2(72)

= 252

Answer 2

But, to answer the question,

T7 = 12+6*8 = 60