Réponse :
Explications :
Bjr,
168 = 2*2*2 *3*7
168/2 = 84
84/2= 42
42/2 = 21
21/3 = 7
180/2 = 90
90/2= 45
45/3= 15
15/3 = 5
180 = 2*2*3*3*5
en commun:
2*2*2 *3*7
2*2*3*3*5
Soit 2*2*3 = 12
168/12 = 14
180/12 = 15
168/180 => 14/15
b)
5mn15 = 5*60 + 15=> 315s
8mn15 = 8*60 + 15 =>495s
315 , 630,945, 1260, 1575, 1890,2205,2520,2835, 3150,3465
495, 990,1485, 1980, 2475, 2970,3465
Au bout de 3465s
=> 3465/60 = 57mn et45s
☺
