When can you use proportional reasoning to solve ? PLZZ HELP.

When two quantities add to 1

When one quantity is a constant multiple of the other

When the two quantities multiplied equal a constant

When one quantity is 1 more than the other a problem?

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