Given: x and y are real numbers I. Given: x2–1=0 It gives no information about y. ∴ I alone is not sufficient. II. Given: y3–1=0 It gives no information about x. ∴ ΙΙ. alone is not sufficient. I & II, x2–1=0,y3–1=0 x=−1[–1<(+1)] and y=1 x<y ∴ I & II together are sufficient.