Explanation:
Miss K has already graded 10 tests and is grading 9 every hour. We will add keep adding 9 starting from 10.
Mr. T has already graded 22 tests and is grading 7 per hour. We will keep adding 7 starting from 22.
Miss K: 19, 27, 36. ( Took 3 hours to reach 36 tests)
Mr T: 29, 36. (Took 2 hours to reach 36 tests)
It will take Miss K 3 hours and Mr T 2 hours to have graded the same amount of tests (36).
Sorry if I'm wrong