im having tuna pasta salad for lunch, only the only tuna i have in is a 130g john west in sunflower oil. on SW tools its 6.5syns for a 185g tin of tuna. iv made it all up but im only going to eat half as the other half iv put in a lunchbox in the fridge for tomorrows lunch. because im only eating half, do i halve the syns? 