bonjour
ouvrier = x
contremaître = x + 400
patron = x + 400 + 1000 = x + 1 400
11 x + 2 ( x + 400 ) + x + 1 400 = 19 000
11 x + 2 x + 800 + x + 1 400 = 19 000
14 x = 19 000 - 1 400 - 800
14 x = 16 800
x = 1 200
ouvrier = 1 200 €
contremaître = 1 600
patron = 2 200