rochie= r
fusta = f
bluza = b
r+f=200 ecuatia 1
f+b=154 ecuatia 2
f+b+r=296 ecuatia 3
adunand primele 2 ecuatii obtinem r+2f+b=200+154=354
din ecuatia nou rezultata scadem ecuatia 3 si avem r+2f+b- f-r-b=354-296
f=58 lei
r+f=r+58=200 => r=200-58=142
f+b=58+b=154 => b=154-58=98
pentru a ne verifica adunam suma lor
f+b+r=58+142+98=296
