Question

can someone please help me... I need to pass math.
what is the sum of the series?


A. -220
B. -110
C. -95
D. 110

Answer 1

\[\sum_{n-1}^{20} (5-1)\]

Answer 2

that 1 in the parenthesis is supposed to be an n

Answer 3

I did the equation but when I add all the number up I get a weird number not one that i need.

Answer 4

That's an arithmetic sequence because it's linear. You can use this formula