Below is an instruction that describes a task, paired with an input that provides further context. Write a response that appropriately completes the request.

### Instruction:

Convert text to sql: What is the sum of hours for projects that scientists with the name Michael Rogers or Carol Smith are assigned to? | scientists : ssn , name | projects : code , name , hours | assignedto : scientist , project | assignedto.project = projects.code | assignedto.scientist = scientists.ssn | 

### Response:

select sum ( _ ) from _ where _ | select sum ( projects.hours ) from assignedto join projects on assignedto.project = projects.code join scientists on assignedto.scientist = scientists.ssn where scientists.name = 'Michael Rogers' or scientists.name = 'Carol Smith'