a)90-y=y+40
-y-y=40-90
-2y= -50
2y=50
y=25
b)suplementul unghiului de 150= 180-150=30
complementul suplementului <150 90-30=60 grade
c)(90-x)+(180-x)=110
-2x +270=110
-2x=110-270
-2x= -160
2x=160
x=80
d)a/b=5
a=5b
a+b=180
5b+b=180
6b=180
b=30
a=30*5=150
e)a=4b
a+b=90
4b+b=90
5b=90
b=18
a=18*4= 72