Which of these are equivalent to each other? 9x-3x 12x-4 5x+x

Anyone know? will mark brainliest if correct

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

[15 points, algebra 2]simplify the complex fraction and find the restrictions.