Evaluate combination and permutations 9c4 and 6p4

Ineeeeed this is due tomorrow and i dont know the answer can you find all the exponents

Afrequency table of grades has five classes (a, b, c, d, f) with frequencies of 3, 13, 14, 5, and 3 respectively. using percentages, what are the relative frequencies of the five classes?

Which expression demonstrates the use of the commutative property of addition in the first step of simplifying the expression (-1+i)+(21+5i)+0