bonjour c'est des calculs de fractions : 3/4+2/5 et 7/3-2/7 merci d'avance

3/4 + 2/5
= (3 x 5)/(4 x 5) + (2 x 4)/(5 x 4)
= 15/20 + 8/20
= 23/20
7/3 - 2/7
= (7 x 7)/(3 x 7) - (2 x 3)/(7 x 3)
= 49/21 - 6/21
= 43/21