Sn=A1(1-r^n)/(1-r)
Sum of a finite geometric series formula
We know the sum, number of terms and rate, so you plug those in.
-255=A1(1-(-4)^4))/(1-(-4)
-255=A1(1-256)/5
-255=A1(-255)/5
-1275=A1(-255)
5=A1
Hope this helped! Let me know if you have any questions.
Answer:

Step-by-step explanation:
19*19=361.
Answer:
$0.98
Step-by-step explanation:
Given data
Cost of sinuses apples = $9.8 for 10 pound
We want to find the cost per pound
Hence
if 10 pounds cost $9.8
1 pound will cost x
cross multiply
x= 9.8/10
x= $0.98
Hence a pound will cost $0.98