Question

O cutie cu 5 bile cantareste 350 g, iar cutia cu 7 bile de acelasi fel cantareste 450 g. Determinati masa cutiei si masa unei bile.

Answer 1

c+5b=350g;
c+7b=450g
⇒se reduce c cu c;
⇒7b-5b=450g-350g
⇒2b=100g⇒b=50g[masa unei bile];
⇒c+5·50g=450g
⇒c+250g=450g
⇒c=450g-350g
⇒c=100g[masa cutiei];

Answer 2

x=cutia,y=bilele
$\left \{ {{x+5y=350} \atop {x+7y=450}} \right.$
Le scadem si obtinem:-2y=-100⇒y=50 g( bila)
x+5y=350
x+250=350⇒x=100 g(cutia)