Sorry for the misleading title,but this is urgent.

This is a RTP question. I want to know if there is any shhort way to decide how to appraoch in these type of questions. I mean I know how to solve them but has this to be hit and try everytime?
Sorry for the misleading title,but this is urgent.

This is a RTP question. I want to know if there is any shhort way to decide how to appraoch in these type of questions. I mean I know how to solve them but has this to be hit and try everytime?