2. 1 middle school, there were 480 freshmen last year, which is 5/6 of junior high school freshmen. This year, junior high school freshmen increased by 2/5, and senior high school freshmen increased by 1/5. Ask how many junior high school freshmen, senior high school freshmen and freshmen are enrolled this year.
3. Party A, Party B and Party C move bricks, with Party A moving 50 more bricks than Party B, with Party C moving three-eighths of the bricks moved by Party B, and Party A, Party B and Party C moving nine-tenths of the total bricks they moved. How many bricks will Party A, Party B and Party C each carry?
4. A factory has a workshop to organize a post technical training competition, with more than 300 participants, among which workshop A accounts for one fifth, workshop B accounts for one third, workshop C accounts for one quarter, and the rest are competitors of workshop D. As a result, workshop A won one eighth, workshop B won one twelfth and workshop C won one fifteenth. Q: How many workers participated in Workshop D?
There are two kinds of grain in the warehouse: A and B, B and A have 3900 kilograms, B is twice as much as A, and more than 100 kilograms. Q: How many kilograms of grain A and B are there in the warehouse?