=bonjour
A = 20 x /2 - 40 /2 + 12 x /4 - 12 /4
= 10 x - 20 + 3 x - 3
= 13 x - 23
B = - 8 + 12 t + 4 t² - 8 t - 7 t + 14
= 4 t² - 3 t + 6
C = 27 x - 3 x² + 45 - 5 x + 8 x - 6 x²
= - 9 x² + 30 x + 45
D = 16 x² + 56 x + 49
E = 36 x² - 60 x + 25
F = 49 x² - 81
I = 4 x² + 24 x + 36 + 10 + 15 x - 14 x - 21 x²
= - 17 x² + 25 x + 46
