Répondre :

A = (3/2 + 3/5 )(5/4 - 4/3) 
= ( 15/10 + 6/10 ) x ( 15/12 - 16/12 )
= 21/10 x (-1/12)
= -21/120
= -7/40

B= (4/3 - 5/2 ) : (- 2/3 + 3/4 )
= ( 8/6 - 15/6 ) : ( -8/12 + 9/12 )
= -7/6 : 1/12
= -7/6 x 12/1
= -84/6
= -14

C=  3/2 + 3/5 x 5/4 - 4/3 
= 3/2 + 15/20 - 4/3
= 3/2 + 3/4 - 4/3
= 9/4 - 4/3
= 11/12

D= 4/3 - 5/2 : (- 2/3) + 3/4 
= 4/3 - 5/2 x (-3/2) + 3/4
= 4/3 + 15/4 + 3/4
= 61/12 + 3/4
= 35/6