A series $\text{S1}$ of five positive integers is such that the third term is half the first term and the fifth term is $20$ more than the first term. In series $\text{S2},$ the nth term defined as the difference between the $(n+1)$ term and the $n^{\text{th}}$ term of series $\text{S1}$, is an arithmetic progression with a common difference of $30$.
Second term of $\text{S2}$ is
- $50$
- $60$
- $70$
- $\text{None of these}$