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2016-03-08T22:33:34+05:30

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Sorry to say that i only know the 23 sum so i am doing that one only.

given that 
sum of the first 6 terms = 42
sum n terms = n/2 [2a + (n-1) d]
here n = 6
6/2 [2a + (6-1) d] = 42
3[2a + 5d] = 42
2a + 5d = 14   -----------------(1)

then 10th term and the 30 term ratio is 1:3
so,
a + 9d / a + 29d = 1/3
3(a + 9d) = a +29d
3a +27d = a + 29d
3a-a = 29d-27d
2a = 2d
a = d ----------------(2)

from the  (1)
2a +5d = 14   from the  (2)
2a + 5a = 14
7a = 14
a = 2
then  d = 2
the first term is 2
the thirteen term = a + 12d
= 2 + 12(2)
= 2 + 24
= 26.

1 5 1
Good job but qns is simple go for hard.
i mean prepare difficult qns for your exam
ok
please make brainlist