Question

daca elevii unei clase stau cate 2 in banca unul sta singur si raman 2 banci goale iar daca stau cate 3 in banca raman 6 banci libere. Cate banci sunt?​

Answer 1

e = nr elevi

b = nr banci

e = 2(b-3)+1

e = 3(b-6)

2(b-3)+1 = 3(b-6)

2b-6+1 = 3b-18

2b-5 = 3b-18

3b-2b = 18-5

b = 13

Answer 2

Răspuns:  13 banci

Explicație pas cu pas:

Notez numarul bancilor cu ,,b"

Datele

2 × ( b - 2 - 1 ) + 1 → cate 2 elevi in banca, raman 2 banci libere si o banca cu un elev

3 × ( b - 6 ) → cate 3 elevi in banca, raman 6 banci libere

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3 × ( b - 6 ) = 2 × ( b - 3 ) + 1 ⇒ elevi

3 × b - 18 = 2 × b - 6 + 1

3 × b - 2 × b = - 5 + 18

b = 13 ( banci )

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2 × ( 13 - 2 - 1 ) + 1 = 2 × 10 + 1 = 21 elevi

sau:

3 × ( 13 - 6 ) = 3 × 7 = 21 elevi