Bonsoir,
A=7/15*3/4-13/20
= 21/60 -13/20
= 21/60 - 39/60
= -18/60 = -3/10
B= -3/5:5/2+17/40
= 3/5 * 2/5 +17/40
= 6/25 +17/40
= 48/200 +85/200
= 133/200
C=2/3+5/3*3/2
= 2/3 + 15/6
= 4/6+15/6
= 19/6
D=(2/3+5/3) *3/2
= 7/3 *3/2
=21/6 = 7/2
E=1+1/2*5-3/4
= 1+5/2 -3/4
= 8/8 +20/8 -6/8
=22/8 = 11/4