Final answer:
By setting up a system of equations for the costs of Caterer A and Caterer B, and solving for the number of guests, we find that both will charge the same amount for 10 guests.
Step-by-step explanation:
To determine for what number of guests will the cost of Caterer A be the same as Caterer B, we need to set up and solve a system of equations. Let's denote the number of guests as x and the total cost for each caterer as y.
The cost for Caterer A can be represented by the equation y = 15x + 100.
The cost for Caterer B can be represented by the equation y = 20x + 50.
Setting these two equations equal to each other, we get:
15x + 100 = 20x + 50
Solving for x, we subtract 15x from both sides:
100 = 5x + 50
Now, subtract 50 from both sides:
50 = 5x
And finally, divide both sides by 5:
x = 10
The number of guests for which both caterers will charge the same amount is 10 guests.