Bonjour,
A = 8a + 10a + 4 + 9 = 18a + 13
B = -5 – 4a – 8a + 10 = -12a +5
C = 4a + 6 + 8a² + 6a + 12 + 4a² + 9 = 12a² +10a +27
D = - 4a – 6 + 12a² + 10 – 6a² + 12a + 4a + 9 = 6a² +12a +13
a=3
18a + 13 = 18* 3+13 = 67
12a² +10a +27
= 12 *3*3+10 *3 +27
= 108+30+27
= 165