Arithmetic sequences & series

Given the arithmetic sequence: 9; 16; 23; … Determine $(a)T_{12}$, and $(b)S_{12}$, the sum of the first 12 terms.

Given the arithmetic sequence: 7; 1; −5; … Determine $(a)T_{15}$, and $(b)S_{15}$, the sum of the first 15 terms.

Given the arithmetic sequence: 9; 17; 25; … Determine $(a)T_{12}$, and $(b)S_{12}$, the sum of the first 12 terms.

Given the arithmetic sequence: 2; 9; 16; … Determine $(a)T_{15}$, and $(b)S_{15}$, the sum of the first 15 terms.

Given the arithmetic sequence: 7; 16; 25; … Determine $(a)T_{12}$, and $(b)S_{12}$, the sum of the first 12 terms.

Given the arithmetic sequence: 5; 11; 17; … Determine $(a)T_{15}$, and $(b)S_{15}$, the sum of the first 15 terms.

Given the arithmetic sequence: 2; 10; 18; … Determine $(a)T_{12}$, and $(b)S_{12}$, the sum of the first 12 terms.

Given the arithmetic sequence: 12; 9; 6; … Determine $(a)T_{15}$, and $(b)S_{15}$, the sum of the first 15 terms.

Given the arithmetic sequence: 4; 7; 10; … Determine $(a)T_{12}$, and $(b)S_{12}$, the sum of the first 12 terms.

Given the arithmetic sequence: 11; 6; 1; … Determine $(a)T_{12}$, and $(b)S_{12}$, the sum of the first 12 terms.

Given the arithmetic sequence: 2; −4; −10; … Determine $(a)T_{12}$, and $(b)S_{12}$, the sum of the first 12 terms.

Given the arithmetic sequence: 3; −1; −5; … Determine $(a)T_{20}$, and $(b)S_{20}$, the sum of the first 20 terms.