Răspuns :
a-b =900
a =4b
4b-b =900
3b =900
b =300
a =4b =4*300 =1200
v ; 1200-300 =900
a =4b
4b-b =900
3b =900
b =300
a =4b =4*300 =1200
v ; 1200-300 =900
[tex]a-b=900
unde a=4b
deci 4b-b=900
3b=900
b=900:3
b=300 =) a = 1200[/tex]