Answer:
x=20, g=100, f=80
Explanation:
when ever somthing is suplementary it means the the answer will euqal to 180 degrees. That means your equation is going to be
3x+40+5x-20=180
8x+20=180
8x=160
x=20
Finding g
3(20)+40
60+40
g=100
FInding f
5(20)-20
100-20
f=80