SOMEONE HELP ME SOLVE THESE 3 MATH PROBLEMS!!!?

the first two are about percentage and second one is about area also describe how u solved them plz ok numero uno is $2,350 IS INVESTED AT 4% SIMPLE INTEREST PER YEAR.HOW MUCH INTEREST WILL HAVE BEEN EARNED IN 3 YEARS? Next question 161 IS 25% OF WHAT NUMBER and the fina question is FIND THE AREA OF A POLYGON WHOSE VERTICES ARE (-2,3), (0,-2), (6,-2) AND (4,3) THANK U AND PLZ HELP I GOTS FINALS