Equivalent fractions are those fractions that when simplified, are the same. They reduce to the same fraction in their simplest form.
For example, 12/15 and 24 /30 are equivalent fractions. They both reduce to 3/5 in their simplest form.
Least common denominator: it is the lowest number you can use in the denominator to create a set of equivalent fractions that all have the same denominator.
For example, if you have 3/5 + 1/4 and want to add them, you need to get a common denominator
3/5 = 6/10 = 9/15=12/20
1/4 =2/8=3/12 =4/16=5/20
We can use equivalent fractions to help us find the common denominator of 20
replace 3/5 with 12/20 and 1/4 with 5/20
3/5 + 1/4 = 12/20 + 5/20 = 17/20