To Find the least common denominator you have to find the multiples of each number
multiple means the product of each factor
so the multiples of 4 would be 4 8 12 16 20
you want to name at least five multiples but if there are not the same multiples you might have to list more
the multiples of 5 would be 5 10 15 20
then I can stop there because I have found two of the same multiples
so now we have our least common denominator which is 20
HOPE THIS HELPS!!!