Answer:
20
Step-by-step explanation:
One way to find the least common multiple of two numbers is to first list the prime factors of each number. Then multiply each factor the greatest number of times it occurs in either number. If the same factor occurs more than once in both numbers, you multiply the factor the greatest number of times it occurs.
When you make a list it will look something like this::
5-5,10,15,20
20-20
