Answer:
45+10x = y
Step-by-step explanation:
$45 -- stays the same no matter what so that's constant.
$10 -- this varies dependent on the number of vaccinations your dog needs, so you'd use a variable to represent the number of vaccinations (in this case I'm using variable "x").
So, for example if your dog needed 7 vaccinations, it would be: 45+10(7) = y -- answer being $115.
