What is the perimeter of triangle RST?

Isabella earned $190 during the second week. All you do is fit the puzzle pieces together until you only have one piece left. You know how much she's worked in total, that's 50 hours. If she's already worked 30, she only has 20 more to go. Find out the hourly pay by dividing the $285 dollars she already earned by the number of hours she worked, which is 30. That comes out to be 9.50, so if you multiply that by the 20 hours she has left, you get 190! I hope that makes sense to you :)