<span>2(30)+2x=860
This is because the 4 sides of the rectangle add up to the perimeter.
The unknown side is x, and there are two of those, and there are also two sides of 30.
They all add up to the perimeter.
So:
2(30) + 2x = 860</span>
Number one would be x=4, I hope this helps
Answer:
all work is shown and pictured
