Répondre :
A= 5/18-(5/36-1/36)
= 5/18-4/36
= 5/18-1/9
= 5/18-1x2/9x2
= 3/18
= 1/6
B= 17/12-(11/12-1/3)
= 17/12-(11/12-1x4/3x4)
= 17/12-7/12
= 10/12
= 5/6
C= 11/6-2/3+1/6
= 11/6-2x2/3x2+1/6
= 8/6
= 4/3
D= 23/8-3/4-1/2
= 23/8-3x2/4x2-1x4/2x4
= 23/8-6/8-4/8
= 13/8