Question

Daca elevii unei clase se asaza cate ulun in banca,raman 13 elevi in picioare,iar daca se asaza cate doi elevi intr-o banca,raman 2 banci libere.Cati elevi si cate banci erau?

Answer 1

nr elevilor =E
nr bancilor =B
=> E =B +13
     E:2=(B-2) => E=2*B-4   => B+13 =2*B-4 => 17=B (sunt 17 banci)
=> E=B+13=17+13 =30 de elevi
facand proba... 30 de elevi in 17 banci (cate 1 in banca) raman
30-17=13 elevi in picioare
30 de elevi (cate 2 in banca)  => 30:2 =15 banci ocupate, si mai raman 17-15=2 banci libere.