An online bookshop uses Salesforce to track customer sales history. The shop utilizes opportunities to track items and the account object to store customer information.

The shop needs to find the total sum of all opportunities placed by their premium customers. The management team requires this sum to consider providing additional discounts for their premium customers.

Complete the apex code to accept the platinum customer record ids as input and return the sum of all opportunities in response.

Input params
Set <Id>

Output
Decimal