Réponse :
120 2x2x2x3x5 2x2x2 8
------ = ---------------- = ----------- = ------
105 3x5x7 7 7
180 2x2x3x3x5 2x5 10
------ = ------------------ = -------- = -----
162 2x3x3x3x3 3x3 9
