Answer:
60°
Step-by-step explanation:
Given :
DAB= (180 – 3x) °,
mZ B= (6x – 40) °, and
m ZC = (x+20) °.
DAB = mZ B + m ZC ( the exterior angle equal the sum of the two opposite interior angles)
180 - 3x = (6x - 40) + (x + 20)
180 - 3x = 6x - 40 + x + 20
180 - 3x = 6x + x - 40 + 20
180 - 3x = 7x - 20
180 + 20 = 7x + 3x
200 = 10x
x = 200/10
x = 20
Angle B = 6x - 40 = 6(20) - 40 = 120 - 40 = 80
Angle C = x + 20 = 20 + 20 = 40
BAC = 180 - (80 + 40) (SUM OF ANGLES IN A TRIANGLE)
BAC = 180 - 120
BAC = 60°
