bonjour je suis en 4 ème et j'ai besoin d'aide c'est un devoirs en mathe à rendre pour demain le mercredi faite vite svp1​

Bonjour

1)

A = 7/8 x 3/4

A = 21/24

A = (3 x 7) / (3 x 8)

A = 7/8

B = 4/3 x 7/5

B = 21/15

B = (3 x 7) / (3 x 5)

B = 7/5

C = 1/5 x 8/7

C = 8/35

D = 5 x 72

D = 35/2

E = 3/8 x 5

E = 15/40

E = (5 x 3) / (5 x 8)

E = 3/8

F = 0,7/3 x 1/4

F = 0,7/12

F = (0,7 x 10) / (12 x 10)

F = 7/120

2)

a. 17/3 x 4/17

= 68/21

b. 7/11 x 11/7

= 77/77

= 1

c. 45/14 x 42/75

= 1890/1050

= (210 x 9) / (210 x 5)

= 9/5

d. 27/26 x 65/72

= 1755/1872

= (117 x 15) / (117 x 16)

= 15/16

e. 2 x 5/8

= 10/8

= (2 x 5) / (2 x 4)

= 5/4

f. 5,1/4 x 8

= 40,8/4

= (40,8 x 10) / (4 x 10)

= 408/40

= (8 x 51) / (8 x 5)

= 51/5.