Answer:
The answer is 75 guests.
Explanation:
Let the number of guests be represented by g.
Company A charges $500 plus $20 per guest. Equation forms:
......(1)
Company B charges $800 plus $16 per guest. Equation forms:
......(2)
To know the number of guests to get the total costs of both companies as same, we will equal both equations:

Solving for g;

=>

=> g = 75
Hence, 75 guests are needed to get costs for both companies same.