Răspuns :
a - b=400
a =6b
6b - b= 400
5b= 400
b= 400 : 5
b= 80
a=6x80
a=480
verificare:
480- 80= 400
a =6b
6b - b= 400
5b= 400
b= 400 : 5
b= 80
a=6x80
a=480
verificare:
480- 80= 400