Answer:30
Step-by-step explanation:
Hello there!
~I hope you and your family are staying safe and healthy!

We need to start by saying that y = 3
or 
Thus, the equation above is in the two variable form where y = 3
Thus, the required equation is 
Let me know if you have additional questions!
~Garebear
I think you'd do $1500x4=$6000