Répondre :
10/12 + 3/4 = 10/12 + 9/12
= (10 + 9)/12
= 19/12
11/20 + 3/5 = 11/20 + 12/20
= 23/20
1/4 + 7/16 = 4/16 + 7/16
= 11/16
7/24 + 5/8 = 7/24 + 15/24
= 22/24
= 11/12
5/10 + 16/30 = 15/30 + 16/30
= 31/30