AC is congruent to AD
So,
Angle C = Angle D
C= 5x+1
D = 7x-27
5x+1 = 7x-27
Solve for x:
1+27 = 7x-5x
28 = 2x
28/2 = x
x= 14
Replace x in the Angle expressions:
A = 3x-4 = 3(14)-4 = 42-4 = 38
C= 5x+1 = 5(14)+1 = 70+1 =71
D= 7x-27 = 7(14 )-27 = 98-27 = 71
A=38°
C=71°
D= 71°