bjr
a=9
b=8
c =2
2a(b-c) = 2 x a x (b - c) = 2 x 9 x (8 - 2)
= 18 x 6 = 108
4a-3b+2c = 4 xa - 3 x b + 2 x c = 4 x 9 - 3 x 8 + 2 x 2
= 36 - 24 + 4
= 36 + 4 - 24 = 40 - 24 = 16
et
a-b/2c = a - (b / 2xc) = 9 - (8 / (2x2)) = 9 - 8/4 = 9 - 2 = 1
plus clair maintenant ?