Bonjour,
a. 1 - - 7/3
= 1 + 7/3
= (1 x 3) / (1 x 3) - 7/3
= 3/3 - 7/3
= 4/3
b. - 2/3 + 7/8 - 5/6
= (- 2 x 8) / (3 x 8) + (7 x 3) / (8 x 3) - (5 x 4) / (6 x 4)
= - 16/24 + 21/24 - 20/24
= - 36/24 + 21/24
= - 15/24
= (3 x - 5) / (3 x 8)
= - 5/8
c. - 2/10 + 7/25
= (- 2 x 5) / (10 x 5) + (7 x 2) / (25 x 2)
= - 10/50 + 14/50
= 4/50
d. 3/7 - 7/10
= (3 x 10) / (7 x 10) - (7 x 7) / (10 x 7)
= 30/70 - 49/70
= - 19/70.
