Réponse:

Réponse :

Bonsoir,

5/7 + 3/7 = 8/7

1/3+1 = 1/3 + 3/3 = 4/3

2/5 + 7/15 = 6/15 + 7/15 = 13/15

(3+2)/5 + 5/9 = 5/5 + 5/9 = 45/45 + 25/45 = 65/45= 13/9

ou

2/5 +3 +5/9 = 17/5 +5/9 = 153/45 + 25/45 = 178/45

1 - 2/5 = 5/5 - 2/5 = 3/5

ou

(1-2)/5= -1/5

5/7- 7/21 = 15/21 - 7/21 = 8/21

2/10 - 11/100 = 20/100 - 11/100 = 9/100

7/3 - 2/6 - 5/12 = 28/12 - 4/12 - 5/12= 28/12-9/12= 19/12

Explications étape par étape:

Le "ou" signale que je ne savais pas laquelle vous avez.