Dvadeset pet deka is two hundred and fifty grams – that is, twenty-five times ten grams.
You take the fat walnut and turn it into a dessert without a radio, stuff it all into a plastic bottle and cover it so it does not go cold. Nut and dessert give you dvadeset, the bottle gives you pet, and covering it gives you deka.
You already know all three building blocks individually – only the order is new.