if the ratio of the 11th term of an A.P. to its 18th term is 2:3 then find the ratio of the sum of the first five terms to the sum of its first 10 terms
if the ratio of the 11th term of an A.P. to its 18th term is 2:3 then find the ratio of the sum of the first five terms to the sum of its first 10 terms