Greetings from Brasil...
The perimeter is the sum of all sides of the triangle. In this case
P = (2X) + (X) + (4X - 9)
as P = 89
89 = (2X) + (X) + (4X - 9)
89 = 7X - 9
7X = 98
X = 98/7
X = 14
X:
X meters = X = 14
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2X:
2X meters = 2 · X = 2 · 14 = 28
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(4X - 9):
(4X - 9) meters = (4 · X - 9) = (4 · 14 - 9) = (56 - 9) = 47