What are some advantages to writing a direct variation equation rather than solving a problem using a proportion

I’m still confused on how to work the percentages

Triangle dog was rotated to create triangle d'o'g'. describe the transformation using details and degrees.

Jake volunteers to out his younger brother's basketball team in his free time. one of his tasks is to ensure that all the basketballs have enough air in them. given that a properly inflated basketball measures 8.8 inches across, what is the total volume of air inside six of jake’s basketballs? assume that the wall of each ball is infinitely thin.