Answer:
x=45 degrees
y=60 degrees
z=75 degrees
Step-by-step explanation:
x+y+z=180
y+z=3x
So:
in x+(y+z) =180
x + 3x= 180
4x=180
x=180÷4
x=45 degrees
y+z=180-45=135
z is 15 more than y
y+y+15=135
2y+15=135
2y=120
y=120÷2=60 degrees
z=y+15=60+15=75 degrees