RESOLUCIÓN:
[tex]θ - \alpha = 70 \\ θ + \alpha = 90 \\ - - - - - \\ θ - \alpha + θ + \alpha = 70 + 90 \\ 2θ = 160 \\ θ = \frac{160}{2} \\ θ = 80[/tex]
[tex]x + θ + θ = 180 \\ x + 80 + 80 = 180 \\ x + 160 = 180 \\ x = 180 - 160 \\ x = 20[/tex]
RESPUESTA:
X = 20°
