Question

Daca intr o sala se asaza cate un elev in banca, raman 6 elevi in picioare. Daca se asaza 2 in banca iar in una unul singur raman 4 banci libere

Answer 1

Numarul de elevi este acelasi in ambele cazuri
E= numarul de elevi
b=bancile
E=1 xb +6
E=2xb - 2x4-1
1xb+6=3b-9
 b-2b=-8-6-1
-b=-15
b=15
15 banci
E=1x15+6=21
E=2x14-8-1=21
21elevi

Answer 2

$x \to nr. \ de \ banci \\\\ x+6 \to nr. \ de \ copii \\ 2(x-4)-1 \to nr. \ de \ copii \\\\\\ x+6=2(x-4)-1 \\\\ x+6=2x-8-1 \\\\ x+6=2x-9 \\\\ x-2x=-9-6 \\\\ -x=-15 \\\\ \boxed{x=15} \\\\ x+6=15+6 \longrightarrow \boxed{21 \ copii}$