A= 7+9/5-3
= 16/2
= 8*2/2
= 8
B= 14/2 - 4/8
= 14*8/2*8 - 4*2/8*2
= 112/16 - 8/16
= 104/16
= 13*8/8*2
= 13/2
C= 1+ 12+15/3
= 1 + 27/3
= 1*3/3 + 27/3
= 3/3 + 27/3
= 30/3
= 10*3/3
= 10
D= 23-5/2 - 1/2
= 18/2 - 1/2
= 17/2
= 8,5
* c'est le signe de multiplication.