(A) The ratio of the 11‌th ‌ term to the 18‌th ‌ term of an A.P. is 2:3. Find the ratio of the 5‌th ‌ term to the 21‌st ‌ term. Also, find the ratio of the sum of first 5 terms to the sum of first 21 terms.
OR
(B) If the sum of first 6 terms of an A.P. is 36 and that of the first 16 terms is 256 , find the sum of first 10 terms.