Question

a+b+c=80 ,a:b = 1 rest c , c= b - 20

Answer 1

a:b = 1 rest c⇒a=b·1+c⇒a=b+c
a+b+c=80⇒b+c+b+c=80⇒2(b+c)=80⇒b+c=40
c=b-20⇒b+b-20=40⇒2b=40+20⇒2b=60⇒b=30
c=b-20=30-20=10
a=b+c=30+10=40