Before you can add or subtract fractions with different denominators.you first have to find common denominators. subtract the numerators and reduce fraction.
Adding fractions make sure numbers are same add the numerators and put it over the denominator,simplify the fraction if needed
You would hav to get 4% higher which Would get u to a c+
The mean doesn't have outliers, and if you're looking for a perfect middle of your data, the median is the best.
286 and 446 :) hope it helps