"He works at a restaurant at a coast."
Translation:Han arbejder på en restaurant ved en kyst.
So could you also say, "Han arbejder ved en restaurant på en kyst." Are ved and på completely interchangeable?
på kysten = on the coast
ved kysten = at/by the coast
In this case, the meaning is more or less the same.
The English sentence is awkward, people say ".. On the coast", and never ".. At a coast".
Why is på en restaurant på en kyst wrong in this case. På is at or on and as noted the correct English is on the coast. I think of ved as by or at and in this instance the meaning in English is on, phyically at the coast.