Answer:
xn = n·(n + 1)/2
Step-by-step explanation:
The truck should park 6 feet away from the door
P/-3+(-8)=-8
p/-3-8=-8
Add 8 to each side
p/-3-8+8=-8+8
p/-3=0
Multiply both side by 3
p/-3(3)=0(3)
p=0
Check:
p/-3+(-8)=-8
Substitute p with 0
0/-3+(-8)=-8
0-8=-8
-8=-8. As a result, p=0. Hope it help!