Answer:
Sum is 20,935.
Step-by-step explanation:
This is an arithmetic progression.
Sum:
[tex]S = \frac{n}{2} (2a + (n - 1)d) [/tex]
n is the number of terms, n = 79
S is the sum
a is the first term, a = -8
d is common difference, d = -1-(-8) = 7
substitute:
[tex]S = \frac{79}{2} (2 \times - 8 + (79 - 1) \times 7)) \\ \\ S = \frac{79}{2} ( - 16 + 546) \\ \\ S = \frac{79}{2} (530) \\ S = 20935[/tex]
