2/3a² + 1/3ab - 1/4b², -a2 - 2/3ab² + 2b² and 2/3a² - ab - 5/4b² solve with explanition plz plz plz

Which expression gives the area of the triangle shown below

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

In the diagram below,abc is congruent to dec what is the value of x