When is the diffrence of two decimals an interger

Enter the number of complex zeros for the polynomial function in the box. f(x) = x+ + 5x² +6

Last year, a state university received 3,560 applications from boys. of those applications, 35 percent were from boys who lived in other states. part a)how many applications did the university receive from boys who lived in other states? part b)applications to the university from boys represented 40percent of all applications. how many applications did the university receive in all? i don't how to do part b so me and plz tell how you got your answer

What can you determine about the solutions of this system