The sum of n terms of arithmetic progressions are in the ratio (3n+ 8): (7n+ 15). Find the ratio of their 12th terms.

The sums of n terms of two arithmetic progressions are in the ratio 5n+ 4 : 9n + 6 . Find the ratio of their 18th terms.

The sums of n terms of two arithmetic progresssions are in the ratio (7n+1):(4n+17). Find the ratio of their mth terms.

The sum of n terms of two arithmetic series are in the ratio of (7n + 1)/(4n + 27) . Find the ratio of their 12th terms.

If the sum of n terms of two arithmetic series are in the ratio. ,- (6n + 1) : (4n + 21). Find the ratio of their 8th term.

If the sum of n terms of two arithmetic series are in the ratio. ,- (2 + 3n) : (3 + 2n). Find the ratio of their 7th term.

The sums of n terms of two AP's are in the ratio (3n-13):(5n+21). Find the ratio of their 24th terms.

If the sum of n terms of two A.P.s are in the ratio 7n + 1 : 4n + 27. Find the ratio of their 11^(th) terms.

If the ratio of sum of m terms of an A.P. to the sum of n terms is (2m + 1) : (3n +1), find the ratio of 7th to 10th term

Soppose that all the terms of an arithmetic progression (AP) are natural numbers. If the ratio of the sum of the first seven terms to the sum of the first eleven terms is 6:11 and the seventh term lies between 130 and 140, then the common difference of this AP is