2 exercice de fraction Niveau 5ème svp

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29)

a. 3/5 = (3 x 7) / (5 x 7) = 21/35

b. 3/4 = (3 x 15) / (4 x 15) = 45/60

c. 80/100 = (80 : 20) / (100 : 20) = 4/5

d. 49/21 = (49 / 7) / (21 : 7) = 7/3.

30)

a. 4/3 = (4 x 5) / (3 x 5) = 20/15

b. 5/6 = (5 x 6) / (6 x 6) = 30/36

c. 3,4/7,8 = (3,4 x 10) / (7,8 x 10) = 34/78

d. 56/24 = (8 x 7) / (8 x 3) = 7/3

e. 72/45 = (9 x 8) / (9 x 5) = 8/5.