PLEASE HELP!!!

Kellys needs to order lunch for orders 6 people at a business meeting. Her menu choices are chicken salad for a cost of $5 per person and egg salad for a cost of $4 per person. She only has $28 to spend. More people want chicken salad.

Write one equation in a system for this situation.

Write a second equation in the system.

PLEASE EXPLAIN, thanks ♡