LCM and HCF of two numbers are 90 and 15 respectively.  If the sum of the two numbers is 75, then find the smallest number?

30

LCM = HCF (ab)                   HCF (a + b) = 75

  90 = 15 (ab)                        15 (a + b) = 75

   ab = 6                                       a + b = 5

Let, a = 2, b = 3

Therefore, smallest no. = 15 × 2 = 30