Notez b = nr. banci
2 × b + 9 = nr. calatori → relatia ( 1 )
3 × ( b - 1 - 2 ) + 1 = nr. calatori → relatia ( 2 )
⇒ 3 × ( b - 3 ) + 1 = 2 × b + 9
3 × b - 9 + 1 = 2 × b + 9
3 × b - 2 × b = 9 + 8
b = 17 banci sunt in autocar
2 × 17 + 9 = 34 + 9 = 43 calatori
Verific:
3 × ( 17 - 1 - 2 ) + 1 calator pe o banca = 3 × 14 + 1 = 43 calatori