Radu, Nicu si Mihaela au participat la un concurs de matematica pe echipe. Radu si Nicu au rezolvat 7 probleme,Nicu si Mihaela 8 probleme, iar Radu si Mihaela 5.
Cate probleme a rezolvat fiecare copil ?

Fie r, n, m numarul problemelor rezolvate de fiecare copil.
r+n=7
n+m=8
r+m=5
=>r+n+n+m+r+m=7+8+5
2r+2n+2m=20 (impartim prin 2)
=>r+n+m=10
r+n=7 =>7+m=10
m=10-7=3 probleme a rezolvat Mihaela
r+m=5 =>r+3=5
r=5-3=2 probleme a rezolvat Radu
r+n=7 =>2+n=7
n=7-2=5 probleme a rezolvat Nicu

Answer Link

Geoman2005 Geoman2005 · Answer 2 · 2017-03-26T11:49:40+03:00

R ---------- N ------------------------ 7 probleme
N --------- M ----------- 8 probleme
R ----------------------- M ----------- 5 probleme
=================================
2R ------- 2N --------- 2M --------- 20 probleme

R --------- N ---------- M ----------- 10 probleme
N ---------- M ----------- 8 probleme
==================================
R = 10-8= 2 probleme

R --------- N ---------- M ----------- 10 probleme
R ----------------------- M ----------- 5 probleme
==================================
N = 10-5 = 5 probleme

R --------- N ---------- M ----------- 10 probleme
R ---------- N ------------------------ 7 probleme
===================================
M=10-7=3 probleme