Answer:
x = 9
∠B = 7 x 9 - 1 = 62°
∠BCD = 120°
Step-by-step explanation:
exterior angle of a triangle is equal to the sum of two opposite interior angles
∠BCD = ∠CBA + ∠BAC
10x + 30 = (7x - 1) + (58)
10x + 30 = 7x + 57
3x = 27
x = 9
∠B = 7 x 9 - 1 = 62
∠BCD = 10 x 9 + 30 = 120
