If the $10^{\text{th}}$ term of an A.P. is $\frac{1}{20}$, and its $20^{\text{th}}$ term is $\frac{1}{10}$, then the sum of its first 200 terms is. (1) 50 (2) $50\frac{1}{4}$ (3) 100 (4) $100\frac{1}{2}$
If the $10^{\text{th}}$ term of an A.P. is $\frac{1}{20}$, and its $20^{\text{th}}$ term is $\frac{1}{10}$, then the sum of its first 200 terms is.\\
(1) 50\\
(2) $50\frac{1}{4}$\\
(3) 100\\
(4) $100\frac{1}{2}$