bonsoir
ados = x
adulte = x + 10.5
enfant = x - 14
14 ( x + 10.5 ) + 18 x + 8 ( x - 14 ) = 1 425
14 x + 147 + 18 x + 8 x - 112 = 1 425
40 x = 1 425 - 147 + 112
40 x = 1 390
x = 34.75
ados = 34.75
adultes = 45.25
enfants = 20.75
18 * 34.75 + 14 * 45.25 + 8 * 20.75
= 625.5 + 633.5 + 166 = 1 425