"Summen af mad er ikke nok."
Translation:The amount of food is not enough.
The word "summen", 'the sum', makes no sense when talking about food - you don't quantify food with numbers, unless you talk about "the number of burgers". It's like "the number of money..." -doesn't work.
"Tilstrækkelig" and "nok" would be just fine using, if the food is an amount, "Mængden".