Concept:Evaluate fractional exponents by converting them to roots, then substitute given values.Explanation:Given x=64 and y=27.Substitute into y−x32x21−y31.First, simplify each term:x21=6421=64=8y31=2731=327=3x32=6432=(364)2=42=16Now substitute these values into the expression:27−168−3=115Answer:115So the correct option is C.