I am having a problem on a week 3 lab exercise

I am taking the coursera Supervised Machine Learning: Regression and Classification. I am taking the Week 3 practice lab: Logistic regression. I am stuck on the lab step Def Predict. The step tells us to do the Def Compute Cost as we earlier did.

The earlier step gave us the data (x, y, w, b). However the Def Predict only gives (x, w, b). I tried coding cost as I did earlier and followed the hints in the exercise, but I am getting errors. I need help.|

Please post a screen capture image that shows the error messages.