process model error expression

I am working on build an application: step 9 of the Acme Auto App. Currently working on the Process Model. 

When I save and publish I get 2 errors:

The first one says that "there was an error in an expression in at:" but gives me no further information. When I click on it it takes me to properties but I don't know where to look. I checked the troubleshooting suggested on the lesson but did not find anything. What can I do to fix it?

The second it says the process model contains a variable that it does not reference. I'm assuming this is because I will reference this variable later but I am no 100% sure. Is that correct?

Thanks in advance,

Gabriel