Asda Sauce mixes

Can someone please help me work out the syns for this sauce mix, am i supposed to choose the per 100g or per serving on the calculator?

Per 100g
Cals 336
Protein 7.8
Carbs 70.4
Fat 1.4
Packet 40g

Per Serving(serves 4)
cals 33
Protein 0.8
carbs 7.0
fat 0.1
packet 40g

It comes out 6.5 syns with the 100g details so if i dont eat the whole packet i can half the syns?

Are there any free foods in sauce, if not i'd use the calories per portion...

So it says its serves 4 at 33 calories each so that would be 1.5 syns per serving (1/4 pack).