Answer:
25
The set-up would go something like this:
3 * x = 15
x is our variable that isn't defined, bur by doing some simple math we can determine that "x" is 5 becuase of simple logic and reasoning.
This means that you would also have to multiple the 5 by the 5 as well since we know that for every 3 white cars there is 6l5 blue cars.
this would bring the total to 25z hope this helped :)
