Show me how to set up this and solve

Discussion Assignment:

When solving systems of we have at least two unknowns. A common example of a system of equations is a mixture problem. If I know that the solution I use to clean my car windows is 65% water and 35% cleaner, I have one relationship. If I also know that I only have a 3-liter spray bottle that gives me a second relationship. 

1. What do the unknowns in this system represent and what are the two equations that that need to be solved? 
2. Finally, solve the system of equations.