bonjour
les fractions, un peu inquiétant en 3 ème ...
A = 8/3 - 5/3 : 20/21
a = 8/3 - 5/3 x 21/20
a = 8/3 - 105/60
a = 160/60 - 105/60
a = 55/60 = 11/12
B = ( 2 + 2/3) : ( 4/5 - 2/3)
b = ( 6/3 + 2/3) : ( 12/15 - 10/15)
b = 8/3 : 2/15
b = 8/3 x 15/2
b = 120/6 = 20
5
5 x 3/4 = 15/4
15/4 + 5/8 = 30/8 + 5/8 = 35/8
7/8
7/8 x 3/4 = 21/32
21/32 + 5/8 = 21/32 + 20/32 = 41/32
le dernier encore fraction donc là tu fais