A company has a custom object, Sales, }_Help_Request__c, that has a Lookup relationship to Opportunity. The Seles Help Request__c has a mumber field, Number_ct_Hours__c, that represents the amount…

A roll-up summary field must be created on the *parent* object (`Opportunity`) to summarize child records; creating it on the child object would not achieve the desired aggregation on the `Opportunity`.

While an Apex trigger on the `Opportunity` object could achieve this, it involves more complex logic and higher maintenance compared to a declarative flow, and a trigger on the `Sales_Help_Request__c` would be more efficient for child-to-parent rollups in Apex.

A roll-up summary field on the `Opportunity` object cannot directly sum values from `Sales_Help_Request__c` records because `Sales_Help_Request__c` has a Lookup relationship to `Opportunity`, not a Master-Detail relationship, which is a prerequisite for standard roll-up summary fields.

A record-triggered flow on the `Sales_Help_Request__c` object is the most suitable declarative solution. When a `Sales_Help_Request__c` record is created, updated, or deleted, the flow can query all related `Sales_Help_Request__c` records for the parent `Opportunity`, sum their `Number_of_Hours__c` values, and then update the `total_Hours__c` field on the associated `Opportunity`.