[tex]a_{1} = 10 \\ a _{2}= 6 \\ \\ a_{n} = a_{1} + (n - 1)d \\ a_{2} = a_{1} + d \\ d = a_{2} - a_{1} = 6 - 10 = - 4 \\ \\ a_{16} = a_{1} + 15d = 10 + 15 \times ( - 4) = 10 - 60 = - 50 \\ \\ S_{n} = \frac{a_{1} + a_{n}}{2} n\\ a_{30 } = a_{1} + 29d = 10 + 29 \times ( - 4) = 10 - 116 = - 106 \\ S_{30} = \frac{a_{1} + a_{30}}{2} \times 30 = 15(a_{1} + a_{30}) = \\ = 15 \times (10 - 106) = 15 \times ( - 96) = - 1440[/tex]