\[a_{1} = 5;\ \ a_{2} = 11:\]
\[d = a_{2} - a_{1} = 11 - 5 = 6.\]
\[a_{7} = a_{1} + 6d = 5 + 6 \cdot 6 = 41.\]
\[S_{7} = \frac{(5 + 41) \cdot 7}{2} = \frac{46}{2} \cdot 7 = 23 \cdot 7 = 161.\]
\[Ответ:\ a_{7} = 41;\ \ S_{7} = 161.\]