Répondre :
il faut les mettre au même dénominateur
1 + 5/2 = 2/2 + 5/2 = 7/2
1 + 5/7 = 7/7 + 5/7 = 12/7
1 - 2/3 = 3/3 - 2/3 = 1/3
1 - 8/11 = 11/11 - 8/11 = 3 /11
2 + 5/4 = 8/4 + 5/4 = 13 /4
3 + 4/5 = 15/5 + 4/5 = 19/5
5 - 3 /7 = 35/7 - 3/7 = 32 /7
il faut les mettre au même dénominateur
1 + 5/2 = 2/2 + 5/2 = 7/2
1 + 5/7 = 7/7 + 5/7 = 12/7
1 - 2/3 = 3/3 - 2/3 = 1/3
1 - 8/11 = 11/11 - 8/11 = 3 /11
2 + 5/4 = 8/4 + 5/4 = 13 /4
3 + 4/5 = 15/5 + 4/5 = 19/5
5 - 3 /7 = 35/7 - 3/7 = 32 /7