Michigan State University Algebra Problems Homework

i ‘d like to receive answer in 30mins. only one question and it is very simple. give me the answer before 2:00 PTD.

Suppose : : GX A+ A is a group action, where |G| = 15 and A| = 7.
a) What are the possible sizes of the orbits?
b) Must there exist a € A such that g.a=a for every g € G? Justify your answer.