A company is using Microsoft Power Apps to create a custom application for tracking employee performance metrics. The application needs to calculate the average performance score of employees based on their quarterly evaluations. Each employee\'s score is derived from three different categories: Sales Performance, Customer Feedback, and Team Collaboration. The scores for these categories are weighted differently: Sales Performance contributes 50%, Customer Feedback contributes 30%, and Team Collaboration contributes 20%. If an employee has the following scores: Sales Performance = 80, Customer Feedback = 90, and Team Collaboration = 70, what is the employee\'s overall performance score?