Let the 'a' and 'A' be the first term of two AP's
And 'd' and 'D' be the common difference of the AP with first term as 'a' and 'A' respectively.
Also, let their nth term be an and An and sum of nth terms be sn and Sn.
We know, that sum of first n terms of an an AP is
Where, a is first term and d is common difference
Put n = 2(9) - 1 = 17
[we choose, n = 2m - 1 for calculating ratio of mth terms]
Hence, ratio of 9th terms is 24:19
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