Ok. You can use equations to find out what number of each meal was eaten.
x*14+y*17=99
If you solve for x and y (I used guess and check- there's only a few possible combinations) and got one chicken dinner and five steak dinners.
Answer:

Step-by-step explanation:
1. 
2. 
3. b = 
Can't be simplified.
I think 12 percent but sorry if I got it super wrong