If two numbers are in a 3 to 4 ratio and their greatest common factor is 5, what's their least common multiple?

Question: If two numbers are in a 3 to 4 ratio and their greatest common factor is 5, what's their least common multiple?

Solution:
Given:
The ratio of two numbers = 3 : 4
and HCF = 5

So the numbers are:
3 × 5 = 15 and 4 × 5 = 20

We know,
First number × Second number = LCM × HCF
⇒ 15 × 20 = LCM × 5
⇒ LCM × 5 = 300
⇒ LCM = 300 ÷ 5 = 60