Y is greater than or equal to 0
Answer:
Therefore the friends will have to buy 511 feet of fence (rounding up) or 510 feet of fence ( to the nearest foot).
Step-by-step explanation:
i) perimeter of rectangular yard = 319 feet
ii) perimeter of yard of friends 
iii) Therefore the friends will have to buy 511 feet of fence or 510 feet of fence ( to the nearest foot).
The answer is 10 :) ........
Find and review the slope formula.
The slope of a line segment that connects the points (a, b) and (c, d) is
d-b
m = --------------
c-a
Write out this formula for a=-3, b=-4, c=6 and d=-1.