Question 551574
angle I x 
Angle II 3x
Angle III = x+3x+12= 4x+12

x+3x+4x+12=180 ( sum of angles of triangle = 180 deg.)

8x+12=180
8x=180-12
8x=168
/8
x=21
angle I = 21
Angle II = 63
Angle III = 96