Il faudrait m'aider pour ses deux exercices, merci

Exercice 23 :

A = (3/7)+(5/2)
A = (6/14)+(35/14)
A = 41/14

B = (-5/3)+(7/8)
B = (-40/24)+(21/24)
B = -19/24

C = (-8/5)-(5/3)
C = (-24/15)-(25/15)
C = -49/15

D = (1/9)-(-7/4)
D = (4/36)-(-63/36)
D = 67/36

Exercice 24 :

A = (-13/6)+(9/4)
A = (-52/24)+(36/24)
A = -88/24
A = -11/3

B = (-7/15)+(11/6)
B = (-14/30)+(55/30)
B = 41/30

C = (7/8)+(-11/6)
C = (42/48)-(88/48)
C = -46/48
C = -23/24