Hey!
[tex] \sf \longmapsto S_{ 20} = \dfrac{n}{2} \times 2a + (n - 1)d \\ \\ \sf\longmapsto S_{20}= \dfrac{20}{2} \times 2(2) + (20 - 1)6 \\ \\ \sf\longmapsto S_{20} = 10 \{ 4 + 114 \} \\ \\ \sf \longmapsto \boxed{\bf{S_{20} = 1180}}[/tex]
Hope it helps :)
