Незнаю про ответ, но у меня так

Dim i As Integer, j As Integer, k As Integer
Dim L As Integer
Dim M As Integer
Dim N As Integer
Dim Max As Integer
For i = 0 To Int((74 / 9))'Наименьшее
For j = 0 To Int(50 / 3)'Наименьшее
For k = 0 To Int(74 / 3)'Наименьшее
L = i * 9 + j * 4 + k * 3'Площадь
N = i * 6 + j * 3 + k * 1'Цена
M = i * 5 + j * 2 + k * 1'Прибыль
If L <= 74 And N <= 50 Then
If M >= Max Then Max = M
End If
Next k
Next j
Next i
For i = 0 To Int((74 / 9))
For j = 0 To Int(50 / 3)
For k = 0 To Int(74 / 3)
L = i * 9 + j * 4 + k * 3
N = i * 6 + j * 3 + k * 1
M = i * 5 + j * 2 + k * 1
If L <= 74 And N <= 50 And M = Max Then
MsgBox "Max pribil " & Max & " pri 1-" & i & " sht , 2-" & j & " sht, 3-" & k & " sht ."
End If
Next k
Next j
Next i

Результаты:(Прибыль/Шт1/Шт2/Шт3)
40/7/2/1
40/8/0/0