Réponses

2014-10-18T16:24:59+02:00
A=7-14+8+4-20= 7 + 8 +4 -14-20 = 19 -34 = - 15

B=21-(5-11)= 21 - (-6) = 21 + 6 = 27

C=(-4)x(-7)+12= (-4x-7) +12 = 28 +12 = 40

D= -7+6x(-3)-2+12=
  -7 + (-18) -2 +12= -7 -18 -2 +12 = -27+12 =  -15
2014-10-18T16:26:57+02:00
A= -15
b= 21-(-6)
b= 21+(+6)
b= 21+6
b= +27
c= ((-4)*(-7))+12
c= 28+12
c=+40
d=-7+(6*(-3))-2+12
d= -7+(-18)-2+12
d=-15