Bonjour
a = 28 + 20 = 48
a = 4 * 12 = 48
b = 12 + 15 = 27
b = 3 ( 4 + 5 ) = 3 *9 = 27
c = 40 - 10 = 30
x = 5 * 6 = 30
continue
a = 10 x + 15
b = somme donc pas de distributivité
C = 15 + 6 x
d = 20 x - 8
e = 4 * 10 x = 40 x
f = 4 ( 3 x + 2 ) = 12 x + 8