If the triangles KMN and LMN are congruent:
3 x + y = x + 2 y
8 x - 7 = 5 x + 3 y
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2 x - 3 y = 0 / · (-1)
3 x - 3 y = 7
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- 2 x + 3 y = 0
+
3 x - 3 y = 7
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x = 7,
Hypotenuse KN = LN = 8 · 7 - 7 = 56 - 7 = 49
