Given:
Fixed cost = $150
Additional cost = $22.50
To find:
The equation that showing the cost of the gala depends on the number of attendees.
Solution:
Let x be the number of attendees and y be the cost of the gala.
Total cost = Fixed cost +Variable cost
We have,
Fixed cost = $150
Variable cost = Additional cost × Number of attendees
=

=

Total cost of gala is:

Therefore, the required equation is
.