Bonjour
a. 7/18 + 2/6 + 5/9
= 7/18 + (2 x 3) / (6 x 3) + (5 x 2) / (9 x 2)
= 7/18 + 6/18 + 10/18
= 23/18
b. 9 - 15/2 - 3/2
= (9 x 2) / (1 x 2) - 15/2 - 3/2
= 18/2 - 18/2
= 0
c. 1 - 5/8 + 3/8
= (1 x 8) / (1 x 8) - 2/8
= 8/8 - 2/8
= 6/8
= (2 x 3) / (2 x 4)
= 3/4
d. 8/5 - (1/10 + 2/10)
= (8 x 2) / (5 x 2) - [(1x 2) / (10 x 2) + 2/10]
= 16/10 - (2/10 + 2/10)
= 16/10 - 4/10
= 12/10
= (2 x 6) / (2 x 5)
= 6/5
e. (1/6 + 1/18) - (1/3 - 1/9)
= [(1 x 3) / (6 x 3) + 1/18] - [(1 x 6) / (3 x 6) - (1 x 2) / (9 x 2)]
= (3/18 + 1/18) - (6/18 - 2/18)
= 4/18 - 4/18
= 0.
