Question 310667
a+b+c=180
a=3b
b+c=90,

because a=3b than 3b+b+c=180  
                   b+c=90


c=180-4b
b+c=90

because c=180-4b than b+180-4b=90  ,  -3b=-90, b=30,

now c=180-4b=180-120=60   and a=3b=90.


a+b+c=180,  90+30+60=180