Answer:
d
Step-by-step explanation:
sorry if its wrong
Answer 420.
a, is the first term. d is difference.
Since this is an arithmetic progression, I use this formula.
Un = nth term
Sn = sum of terms.
First find the number of terms, which is 20.
Then use the second formula to find the sum.
It's a Octagon!!!!!!!!!!!!
Answer:
2.54 , 2 , 1/4 , -1.79 , -4
Step-by-step explanation: