An open and shut case noun phrase
A legal matter that is very easy to solve
The house owners didn't lock the doors before going out, and that's why they got broken in. This is an open and shut case.
David's death was an open-and-shut case. The hospital was at fault.
A simple, quick or evasive answer
To be very obvious and easy to notice
Used for expressing something which is extremely simple to figure out or solve.
To be extremely simple, basic, or intuitive without much skill or effort.
Its origin is unknown but the first recorded of the phrase as 'simple, straightforward' was in New Orleans, America, 1841.