Question
Let $S_n$ denote the sum of first $n$ terms of an arithmetic progression. If $S_{20}=790$ and $S_{10}=145$, then $\mathrm{S}_{15}-\mathrm{S}_5$ is :
Let $S_n$ denote the sum of first $n$ terms of an arithmetic progression. If $S_{20}=790$ and $S_{10}=145$, then $\mathrm{S}_{15}-\mathrm{S}_5$ is :