Quelle est la réponse du deuxième exercice

a= 4 +5 x(-3)
a = 4 -15
a = -11

b = (3-5-11) x4
b = (3-16) x4
b = -13x4
b = -52

c = -8-7 x (-4)
c = -8 +28
c = 20

d = -9 +(-15) : (-3) +7
d = -9 + 5+7
d = -9+12
d =3