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bianca si beatrice au impreuna 36 de timbre. Cate timbre are fiecare,stiind ca Bianca are cu 20 mai putine?

Răspuns :

[tex]x+y=36 \\ x=20+y \\ 20+y+y=36 \\ 20+2y=36 \\ 2y=36-20=16 \\ y=16:2 \\ \Rightarrow \boxed{y=8} \\ x=20+y=20+8 \\ \Rightarrow \boxed{x=28}[/tex]