Bonsoir, j'ai besoin d'aide merci beaucoup :) .ex 4 voir photo.

Bonsoir , 
A = 5/4 - 3/16
A = 20/16 - 3/16
A = 17/16
B = 9/10 + -5/2
B = 9/10 + -25/10
B = -16/10
B = - 8/5
C = 1 - 17/15
C = 15/15 - 17/15
C = -2/15
D = 3 + -7/5 - 17/20
D = 60/20 + -28/20 - 17/20
D = 15/20
D = 3/4