Answer:
80°
Step-by-step explanation:
42° + 58° + x = 180° [Angle sum property of triangle]
=> 100 + x = 180
=> x = 180 - 100
=> x = 80 (Ans)
58° + 42° + x = 180° -- (Δ sum property)
100° + x = 180°
x = 180° - 100°
x = 80°
