Répondre :
C= 1/3 - 1/3 x 4/7.
=1/3- 4/21
=7/21-4/21
=3/21
=1/7
D= 6/5 x (7/ 3 - 1/4)
=6/5*(28/12-3/12)
=6/5*25/12
=150/60
=15/6
=5/2
E= ( 1 / 4 + 1/5) x (7 /3 - 1/4)
=(5/20+4/20)*(28/12-3/12)
=9/20*25/12
=3/4*5/4
=15/16
=1/3- 4/21
=7/21-4/21
=3/21
=1/7
D= 6/5 x (7/ 3 - 1/4)
=6/5*(28/12-3/12)
=6/5*25/12
=150/60
=15/6
=5/2
E= ( 1 / 4 + 1/5) x (7 /3 - 1/4)
=(5/20+4/20)*(28/12-3/12)
=9/20*25/12
=3/4*5/4
=15/16