How is adding mixed numbers with unlike denominators the same as adding fractions with unlike denominators? How is it different?

To add a mixed number you must first convert it into a heavy headed fraction eg. 12/4
Then you must find a common denominator for all of the fractions like you normally do for regular addition of fractions
After you have added them you must convert the heavy headed fraction back into a mixed number by seeing how many times the numerator goes into the denominator

What the heck i didn’t know