Answer:
There are 16 hot dogs (and 12 hamburgers).
Explanation:
There's certainly a more efficient way of doing it than the way I did, but with such a small number it's just guess and check.
Let x = the amount of hot dogs. Let y = the amount of hamburgers.
(x*8)+(y*6)=28.
Check#1: 1*8+1*6 = 8+6 = 14. Not 28.
Check#2: 2*8+2*6 = 16+12 = 28!
So, there are 16 hot dogs and 12 hamburgers :)