Bjr besoin d’aide pour le 3 et 4 svp merci

Bonjour,

Exercice 3 :
A = 5/4 + 11/4
A = 16/4
A = 4/1
A = 4

B = 9/7 - 3/7
B = 6/7

C = 6/11 + 5/11 - 8/11
C = 11/11 - 8/11
C = 3/11

D = 65/7 - 17/7
D = 48/7

E = 2/8 + 3/4
E = 2/8 + 6/8
E = 8/8
E = 1

F = 45/10 + 8/10
F = 53/10

Exercice 4 :
G = 7/30 + 3/5
G = 7/30 + 18/30
G = 25/30
G = 5/6

H = 4/9 + 2/45
H = 20/45 + 2/45
H = 22/45

I = 5/15 + 4/3
I = 5/15 + 20/15
I = 25/15
I = 5/3

J = 6/35 - 1/7
J = 6/35 - 5/35
J = -1/35

K = 1/5 - 2/25
K = 5/25 - 2/25
K = 3/25

L = 17/30 - 4/15
L = 17/30 - 8/30
L = 9/30
L = 3/10

M = 5/2 - 17/8
M = 20/8 - 17/8
M = 3/8

N = 5/16 + 7/4
N = 5/16 + 28/16
N = 32/16
N = 8/4
N = 2/1
N = 2

O = 2/21 + 5/7
O = 2/21 + 15/21
O = 17/21

P = 8/3 + 3/27
P = 72/27 + 3/27
P = 75/27
P = 25/9

Q = 7/42 - 1/6
Q = 7/42 - 7/42
Q = 0

R = 13/8 + 3/2
R = 13/8 + 12/8
R = 25/8