Answer:
19 units
Explanation:
A regular polygon has equal-length sides. This fact can be used to solve for the value of x, and for the side length. Knowing the side length, we can find the perimeter.
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side length
5 -2x = 4x +9 . . . . . marked sides are the same length
-4 = 6x . . . . . add 2x -9
-2/3 = x . . . . . divide by 6
5 -2(-2/3) = 5 +4/3 = 6 1/3 . . . . length of one side
perimeter
The perimeter is the sum of the side lengths, or 3 times the length of one side.
P = 3s = 3(6 1/3)
P = 19 . . . . units
The perimeter of the polygon is 19 units.