Two numbers are in ratio 4:5 and their LCM is 180. The smaller number is
Choose the correct choice
A) 9 B) 15 C) 36 D) 45 E) none

Rationale: solution : let two numbers be 4 x and 5 x ; their lcm = 180 and hcf = x ; now , 1 st number * 2 nd number = lcm * hcf or , 4 x * 5 x = 180 * x ; or , 20 x = 180 ; or , x = 9 ; then , the smaller number = 4 * 9 = 36 . answer : option c
Answer: C