Aidez moi svp !!!!! C urgent !!!! Les exercices 97 98 et 99

97)
a) 5/6 - 13/10 - 7/15
 5 x 5 / 6 x 5 - 13 x 3 / 10 x 3 - 7 x 2 / 15 x 2
= 25/30 - 39/30 - 14/30
= 28/30
= 2 x 14 / 2 x 15
= 14/15

b) 7/4 - 2 - 11/6
= 7 x 6 / 4 x 6 - 2 x 24 / 1 x 24 - 11 x 4 / 6 x 4
= 42/24 - 42/24 - 44/24
= 44/24
= 4 x 11 / 4 x 6
= 11/6

98)
a) 1/4 + 3/2 x 5/12
= 1/4 + 15/24
= 1 x 6 / 4 x 6 + 15/24
= 6/24 + 15/24
= 21/24

b) (1 + 1/2) : (1/4 - 3)
= (1 x 2 / 1 x 2 + 1/2) : (1/4 - 3 x 4 / 1 x 4)
= (2/2 + 1/2) : (1/4 - 12/4)
= 3/2 : - 11/4
= 3/2 x - 4/11
= - 12/22
= 2 x - 6 / 2 x 11
= - 6/11

99)
a) 5/3 - 1
   1 - 1/6
= 5/3 - 1 x 3 / 1 x 3
   1 x 6 / 1 x 6 - 1/6
= 5/3 - 3/3
   6/6 - 1/6
= 2/3 : 5/6
= 2/3 x 6/5
= 12/15

b) 3/4 - 1/2 x 5/6
= 3/4 - 5/12
= 3 x 3 / 4 x 3 - 5/12
= 9/12 - 5/12
= 4/12
= 4 x 1 / 4 x 3
= 1/3

c) (3/4 - 1/2) x 5/6
= (3/4 - 1 x 2 / 2 x 2) x 5/6
= (3/4 - 2/4) x 5/6
= 1/4 x 5/6
= 5/24