Aidez-moi SVP : exercice 19 :

A= 7-7 x 5 / 6 x 2 -5
  = 7 -35 / 12 -5
  = -28/7
  = -4 x 7 / 7 x 1
  = -4

B= (4-6) x [5+(3-(-2)) x 2]
  = (4-6) x [5 +5 x 2]
  = (4 -6) x [5+10]
  = -2 x 15
  = -30

C= -7 x (-3)-(-3) x (-5) / 12 : (-3) -2
  = 21 - (+15) / -3,3 -2
  = -6/5,3
  = 60/53