Answer:
71
Explanation:
The congruency statement tells you ...
KL = NO
5x -3 = 4x +7
x = 10 . . . . . . . . add 3-4x to both sides
Then that longest side is ...
4(10)+7 = 47
Corresponding sides are the same length in both triangles. The perimeter is the sum of side lengths:
P = 14 + 10 + 47 = 71
The perimeter of ΔKLM is 71 units.
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Additional comment
A triangle with these side lengths cannot exist. The short sides are too short to connect to the ends of the long side. (The long side must be between 14 and 24 units.) I suggest you talk to your teacher about this problem.