If its not an improper fraction then you cant....
An improper fraction is a fraction. It can't become a proper fraction.
Here is a video tutorial https://www.youtube.com/watch?v=HPetBqWKvZM on how to change an improper fraction to a mixed number.
You change them into improper or topheavy fractions.
You change it into an improper fraction, then simplify it, then if you want to, change it back to a mixed number.
Change the mixed number to an improper fraction and then divide.
You do the numerator divided by the denominator, then simplify the fractions if you can. (this is how you change a improper fraction to a mixed number, you cannot change a proper fraction to a mixed number)
Find it out yourself
I wouldconvert both to improper fraction,find a common multiple (CM),calculate equivalent fraction with CM as the denominator,add the numerators,change the improper fraction to a mixed fraction, if required,simplify the fractional part of the mixed fraction - if appropriate and required.
I don't think you can but, you can change an improper fraction to a decimal.