Here are the basic contents of each table:
Employees: SSN, name, wage rate, and any other relevant data such as job, phone, address, etc.
Shops: This is a lookup table with a code (ShopID) for each shop, the name/location of the shop, and any other pertinent information about the shop, such as the manager's name, phone number, type of work, etc.
Wages: This would be the active table, with the following type of data:
SSN
ShopID
Date of Work
Hours
Pay Amount (hours times currentwage rate which could come from the Employees table)
The Wages table might also include other data you might need to track payments received from the shop and the date it was paid. You could just add a field to each record and enter the date when the shop paid, or you also include other fields to allow for differences in payments and include the amount received and a check off box to indicate if it was settled (in case of disputes).
The relationships are:
One to many: SSN in Employees to SSN in Wages
One to many: ShopID in Shops to ShopID in Wages
Both relationships should automatically update the data in the Wages table if the SSN is changed or the ShopID is changed. Also, deletions in the Employees and Shops tables should not be allowed if there is matching data in the Wages table.