Exercie 78 :

a)

A = 2 / ( 1/2 ) ( Diviser par un nombre c'est multiplier par son inverse donc )

A = 2 * ( 2/1 )

A = 4/1

A = 4

B = 3 / ( 1/3 )

B = 3 * 3/1

B = 9

C = 4 / ( 1/4 )

C = 4 * 4/1

C = 16

b)

D = 5 / ( 1/5 )

D = 5 * ( 5/1 )

D = 25

E = 6 / ( 1/6 )

E = 6 * 6/1

E = 36

F = 7 / ( 1/7 )

F = 7 * 7/1

F = 49

c) 

10 / ( 1/10 ) = 10 * 10/1 = 100

Exercice 80 :

A = 7/2 - 3/4

A = 14/4 - 3/4

A = 11/4

A = 2,75

B = 4/7 + 2

B = 4/7 + 14/7

B = 18/7

B = 2,57

C = 11/4 + 7/18

C = 99/36 + 14/36

C = 113/36

C = 3,14

D = 24/36 * 9/27

D = 216/972

D = 9/2

D = 0,22