Let the two-digit number be 10x+y. According to the question, x+y=10 ...(i) and 10y+x+36=10x+y ⇒ −9y+9x=36 ⇒ x+y=10 ⇒ x−y=4 ...(ii) on adding (i) and (ii), we get ⇒ 2x=14⇒x=7 On putting the value of x in equation (i), we get7+y=10 ⇒ y=3 The required number is 73 which is not divisible by a composite number but a multiple of a prime number. i.e 73 . So only II,