Réponse :
bonsoir
Explications étape par étape :
on calcule chacune les sommes de chacune des figures
7/30 + 3/10 = 7/30 + (3 x 3 )/ (3 x 10)
7/30 + 3/10 = 7/30 + 9/30
7/30 + 3/10 = 16/30 = 8/15
13/7 = 13/7 (fraction irréductible)
19/21 = 19/21 (fraction irréductible)
11/5 - 12/35 = (11 x 7)/(7 x 5) - 12/35
11/5 - 12/35 = 77/35 - 12/35
11/5 - 12/35 = 65/35 = 13/7
36/42 + 1/21 = 36/42 + (2 x 1)/(2 x 21)
36/42 + 1/21 = 36/42 + 2/42
36/42 + 1/21 = 38/42 = 19/21
4 - 10/6 = (4 x 6)/(6 x 1) - 10/6
4 - 10/6 = 24/6 - 10/6 = 14/6 = 7/3
23/15 + 8/3 = 23/15 + ( 8 x 5)/(5 x 3)
23/15 + 8/3 = 23/15 + 40/15
23/15 + 8/3 = 63/15 = 21/5
bonne soirée
