6.6.16 Combinatorics

Problem: Nine students must take a test in four subjects: Physics, Algebra, English and History. All tests are scheduled at the same time and each person can take only one test, so students need to be divided into groups. In how many ways can this be done? In how many ways can they take a sit after the test at two completely identical tables (at least one at a table) in order to celebrate the results?