Question 345195
i'LL ASSUME THAT [C] IS 20 DEGREES LESS THAN B.
A+B+C=180
A=4B
C=B-20 
4B+B+(B-20)=180
6B=180+20
6B=200
B=200/6
B=33.33 ANS.
A=4*33.33=133.33 ANS.
C=33.33-20=13.33 ANS.
PROOF:
133.33+33.33+13.33=180
180~180