Bonjour,
A = 2n + 2(n - 2)
A = 2n + 2n - 4
A = 4n - 4
B = 4(n - 1)
B = 4n - 4
C = n + 2(n - 1) - (2 - n)
C = n + 2n - 2 - 2 + n
C = 4n - 4
On obtient la meme expression en developpant A, B et C.
C = 3(5x + 6) + 8(3 - 2x)
C = 15x + 18 + 24 - 16x
C = -x + 42
Je te laisse faire le dernier :)