Question

so im a bit stuck on this one,A and B. i have gotten 2 very different answers from my fellow classmates, so im coming here to hopefully settle this. how do i go about solving this one? as much detail as possible i really need to have this down befoer the exam next week. also what is a good form of mapping simply (x,y)--> (x\sqrty)? im always unsure how i should state my mapping.