Bonjour,

A = 2/3 + 4/5

A  = (2 x 5) / (3 x 5) + (4 x 3) / (5 x 3)

A = 10/15 + 12/15

A = 22/15

B = 3 - 2/5

B = (3 x 5) / (1 x 5) - 2/5

B = 15/5 - 2/5

B = 13/5

C = 7/3 + 6/12

C = (7 x 4) / (3 x 4) + 6/12

C = 28/12 + 6/12

C = 34/12

C = (2 x 17) / (2 x 6)

C = 17/6

D = 5/24 - 7/16

D = (5 x 2) / (24 x 2) - (7 x 3) / (16 x 3)

D = 10/48 - 21/48

D = - 11/48

E = 7/- 4 x 4/3

E = - 28/12

E = (4 x - 7) / (4 x 3)

E  = - 7/3

F = 3 x 2/5

F = 6/5

G = 2/9 x - 5/3 x 3/- 2

G = - 10/27 x - 3/2

G = 30/54

G = (6 x 5) / (6 x 9)

G = 5/9

H = 4/15 x 25/3 x 9/16

H = 100/45 x 9/16

H = 900/720

H = (180 x 5) / (180 x 4)

H = 5/4

R = 2/3 : 4/5

R = 2/3 x 5/4

R = 10/12

R = (2 x 5) / (2 x 6)

R = 5/6

S = 3 : 12/5

S = 3 x 5/12

S = 15/12

S = (3 x 5) / (3 x 4)

S = 5/4

T = 6/7 : 12

T = 6/7 x 1/12

T = 6/84

T = (6 x 1) / (6 x 14)

T = 1/14

U = 5/3 x 25/9

U = 5/3 x 9/25

U = 45/75

U = (15 x 3) / (15 x 5)

U = 3/5.