w = 0.7  x + 1.2  y

milk = 9  x + 4  y ≤ 3600

coffee = 4  x + 5  y ≤ 2000

sugar = 3  x + 10  y ≤ 3000

sol = 
      NMaximize[{w, 
          milk && coffee && sugar && x ≥ 0 && 
            y ≥ 0}, {x, y}]