Répondre :
bjr
A = 5 x 1/7 = 5/7
et
7/12 + 5/18
commun multiple à 12 et 18 = 36 (12x3 = 36 et 18x2 = 36) donc
7/12 + 5/18 = 7x3/12x3 + 5x2/18x2 = 21/36 + 10/36 = 31/36
et
E = 2 - 1/5 = 10/5 - 1/5 = 9/5
bjr
A = 5 x 1/7 = 5/7
et
7/12 + 5/18
commun multiple à 12 et 18 = 36 (12x3 = 36 et 18x2 = 36) donc
7/12 + 5/18 = 7x3/12x3 + 5x2/18x2 = 21/36 + 10/36 = 31/36
et
E = 2 - 1/5 = 10/5 - 1/5 = 9/5