The ratio of two numbers is 5 : 7 and their HCF is 3. Their LCM is:

75 105 125 35

105

Ratio of two numbers = 5 : 7  H.CF = 3  So, The numbers = 5 × 3 = 15 and second number = 7 × 3 = 21 Now, we know that  Product of two numbers = H.C.F × L.C.M  ⇒  15 × 21 = 3 × L.C.M  L.C.M  = 105