The Ratio Of The 2nd Term To The 7th Term Of An A.P Is 1:3 And Their Sum Is 20.Calculate The Sum Of The 1st Terms Of The G.P

Answer 1

2nd term = a+d
7th term = a+6d

a+d + a+6d = 20
2a + 7d = 20 **

(a+d)/(a+6d) = 1/3
3a + 3d = a + 6d
2a = 3d ***

sub that into **
3d + 7d = 20
10d = 20
d = 2
then 2a = 6
a = 3

"Calculate The Sum Of The 1st Terms Of The G.P"

HUH? I thought we were dealing with an AP.
Isn't the sum of the first term just the first term???