Aidez moi exercice 103 et 104

a=1/7-5/7
a= 4/7

b=1/2+5/6
b=3/6+5/6
b=8/6= 4/3

c=2/5-3/4
c=8/20-15/20
c=-7/20

d= 3/4*7/11
d=3*7/4*11
d=21/44

103)
A = 1/7 - 5/7
A = - 4/7

B = 1/2 + 5/6
B = 1 x 3 / 2 x 3 + 5/6
B = 3/6 + 5/6
B = 8/6
B = 2 x 4 / 2 x 3
B = 4/3

C = 2/5 + 3/4
C = 2 x 4 / 5 x 4 + 3 x 5 / 4 x 5
C = 8/20 + 15/20
C = 23/20

D = 3/4 x 7/11
D = 21/44

E = - 2/15 x 25/6
E = - 50/90
E = 10 x - 5 /10 x 9
E = - 5/9

F = 4/7 : 5/3
F = 4/7 x 3/5
F = 12/35

104)
A = 7/5 - 7/3 x 15/14
A = 7/5 - 105/42
A = 7 x 42 / 5 x 42 - 105 x 5 / 42 x 5
A = 294/210 - 525/210
A = - 301/210
A = 7 x - 43 / 7 x 30
A = - 43/30

B = 8/5 - 3/4 : 9/8
B = 8/5 - 3/4 x 8/9
B = 8/5 - 24/36
B = 8 x 36 / 5 x 36 - 24 x 5 / 36 x 5
B = 288/180 - 120/180
B = 168/180
B = 12 x 14 / 12 x 15
B = 14/15

C = 8/3 - 2/5
         7/5
C = 8 x 5 / 3 x 5 - 2 x 3 / 5 x 3
                     7/5
C = 40/15 - 6/15
           7/5
C = 34/15 : 7/5
C = 34/15 x 5/7
C = 170/105
C = 5 x 34 / 5 x 21
C = 34/21