Bonsoir
a. 2/3 + (- 1/15) = 3/5
car 10/15 - 1/15 = 9/15
b. - 7/4 + 19/8 = 5/8
car - 14/8 + 19/8 = 5/8
c. 9/7 + (- 11/14) = 1/2
car 18/14 - 11/14 = 7/14 = 1/2.
