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