trouver les nombre manquants

bonjour



a) 10/3 + ( -6/3) = 4/3

b) - 12/7 + 5/7 = - 7/7 = - 1

c) 7/15 + 12/15 = 19/15

d) 4/7 x  - 140/84 = - 560/ 588 = - 20/21

e) - 2/5 + 10/15 = - 6/15 + 10/15 = 4/15