19. Dari suatu deret aritmetika, diketahui suku pertama adalah 20 dan suku keenam adalah 40 . Jumlah sepuluh suku pertama dari deret tersebut adalah A. 340 B. 350 C. 360 D. 370 E. 380

1. \( \begin{array}{l}54-(46+7) \\ 37-(24-8)\end{array} \)

Find the \( 12^{\text {th }} \) term of the arithmetic sequence whose common difference is \( d=8 \) and whose first term is \( a_{1}=5 \).

\( \frac{12}{13}+\frac{1}{13}+\frac{10}{13}=\square \) (Type an integer or a fraction.)

Combine. Be sure to simplify your answer whenever possible. \( \frac{11}{18}-\frac{1}{18} \) \( \frac{11}{18}-\frac{1}{18}=\square \) (Type a fraction. Simplify your answer.)

\( \frac{8}{5}-\frac{4}{5}=\square \) (Simplify your answer. Type a fraction.)