Can you post your code using the format instead of posting images. You can use the format button which looks like </>. This way we can copy and paste the code in the challenge on our side to see whats going on
So, the first thing is since you are using building-color-3, and window-color-3 you need to use var because those are variables. Look at the background-color example, see how it is using var? You need to add that to all three of your variables.
Second, you do not need to add any percentages for the first two colors, the only percentage you should be adding is 15% for the last one.