Răspuns: 18 banci si 37 elevi
Explicație pas cu pas:
Notez cu ,,b" = nr. banci
2 × b + 1 = 3 × ( b - 5 - 1 ) + 1 ⇒ elevi
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3 × ( b - 6 ) + 1 = 2 × b + 1
3 × b - 18 + 1 = 2 × b + 1
3 × b - 2 × b = 1 + 17
b = 18 ( banci )
18 × 2 + 1 = 37 elevi
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Verific: 3 × ( 18 - 5 - 1 ) + 1 = 3 × 12 + 1 = 37 elevi