Question 149073
let angle 1 = a
angle 2= b
angle 3=c


a=a
b=3a-10
c=b-10


THEN

a=a
b=3a-10
c=3a-10-10

THEN

a=a
b=3a-10
c=3a-20

AND 
a+b+c=180  (BECAUSE of the definition of a triangle having 180 degrees total angle measure)
SO
a+3a-10+3a-20=180
7a-30=180
7a=210
a=30.

So b=80 and c=70.

Angles are 30, 70, and 80.