Bonsoir,
A = 2/3 + 5/3
A = 7/3
B = 15/3 - 2/9
B = 15 x 3 / 3 x 3 - 2/9
B = 45/9 - 2/9
B = 43/9
C = 2/4 + 3/8 + 1/2
C = 2 x 2 / 4 x 2 + 3/8 + 1 x 4 / 2 x 4
C = 4/8 + 3/8 + 4/8
C = 11/8
D = (2 + 3) x 4 + 4/12
5 + 7
D = 6 x 4 + 4/12
12
D = 24/12 + 4/12
D = 28/12
D = 4 x 7 / 4 x 3
D = 7/3
E = (2 + 5) (5 - 3) - 4/3
21
E = 7 x 2 - 4/3
21
E = 14/21 - 4/3
E = 14/21 - 4 x 7 / 3 x 7
E = 14/21 - 28/21
E = - 14/21
E = 7 x - 2 / 7 x 3
E = - 2/3