Răspuns :
x/3 = 180 - x
4x/3 = 180
x= 3 x 45 = 135°
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Verificare: suplementul(135°) = 45°, 3x45=135° OK
4x/3 = 180
x= 3 x 45 = 135°
________________________
Verificare: suplementul(135°) = 45°, 3x45=135° OK