$1.$Given the following relations:

Employee$($EID$,$ EName, Age, DeptID$)$

Department$($DeptID$,$ DName, Location$)$

Project$($PID$,$ PName, DeptID$)$

Works$\_$On$($EID$,$ PID, Hours$)$

Write the Relational Algebra expression to find the names of employees who have worked more than $20$ hours on a project located in 'New York'.