This Application Problem is a part of the Lesson 17, Unit 4, Grade 5. Ms. Casey grades 4 tests during her lunch. She grades of the remainder after school. If she still has 16 tests to grade after school, how many tests are there? Today's Application Problem recalls Lesson 16's work with tape diagrams. This is a challenging problem in that the value of a part is given and then the value of 2 thirds of the remainder.