EXPLANATION:
Given that :
R ={ (x-1),(x-2) ,x = (2,3,4,5)}
Put x = 2 then (2-1),(2-2) = (1,0)
Put x = 3 then (3-1),(3-2) = (2,1)
Put x = 4 then (4-1),(4-2) = (3,2)
Put x = 5 then (5-1),(5-2) = (4,3)
R = { (1,0),(2,1),(3,2),(4,3)}
Domain = {1,2,3,4}
Range = {0,1,2,3}