x=>y=4/x
1=>y=4/1=4
2=>y=4/2=2
4=>y=4/4=1
6=>y=4/6=2/3
8=>y=4/8=2/4=1/2
b)cand x=1,y=4
cand x=2,y=2
cand x=4,y=1
cand x=6,y=2/3
cand x=8,y=1/2
c) x 1 2 4 6 8
y 4 2 1 2/3 1/2