Bonjour,
tarif adulte: x
tarif enfants: x-4
100*x + 50(x-4) = 1 300
100x +50x -200 = 1 300
100x + 50x = 1 300 +200
150x = 1500
x= 500/150 = 10
tarif adultes: 10€
tarif enfants : 6 €
Vérif:
100*10 + 50*6 = 1 000 =300 =1 300
