Bonjour,
1)
= 5/7
2)
12/27 + 5/27 = 17/27
3)
-9/6 + 14/6 = 5/6
4)
-8/12 - 9/12 = -17/12
5)
-21/75 + 55/75 = 34/75
6)
-45/90 +54/90+40/90 = 49/90
7)
4/7 -2/3 +5/7 = 12/21 -14/21 +15/21 = 13/21
8)
9/18 +6/18 +8/18 -15/18 = 8/18 = 4/9
9)
27/63- 35/63 -252/63 = -260/63
