Respuesta :

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x - the unit
3x; 4x; 5x - the lengths of the sides
3x + 4x + 5x = 30
12x = 30   |:12
x = 2.5
3x = 3 · 2.5 = 7.5 cm
4x = 4 · 2.5 = 10 cm
5x = 5 · 2.5 = 12.5 cm