bonjour, pourriez vous m'aider svp? ​

Bonjour,

a. 3/5 = 3x7/5x7 = 21/35

b.3/4 = 3x15/4x15 = 45/60

c. 80/100 = 80/20/100/20 = 4/5

d. 49/21 = 49/7/21/7 = 7/3