The term –18xy and which other term are like terms?
a.
–18x
b.
4yx
c.
9y
d.
–18

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.