I.Given : 75 is a factor of n. ⇒ n is a multiple of 75. e.g. 75, 150, 225, ....... and so on. ∴ I alone is not sufficient. II. Given : 45 is a factor of n. ⇒ n is a multiple of 45. e.g. 45, 90, 135, 180, 225, ....... and so on. ∴ II alone is not sufficient. I & II. n is a multiple of both 75 and 45. LCM (75, 45) = 225 ⇒ n is a multiple of 225. e.g. 225, 450, 675, ....... Hence, n is divisible by 225 ∴ I & II together are sufficient