motam cu m,e,a necunoscutele (sumele fetelor
avem m+e+a=6800000 lei
m=e-300000⇒e=m+300000
m=a/2+900000⇒a=2m-1800000
inlocuim in prima
m+m+300000+2m-1800000=6800000
4m-1500000=6800000⇒4m=8300000⇒m=2075000
e=2075000+300000=2375000
a=4150000-1800000=2350000
proba 2075000+2375000+2350000=6800000