Answer:
4 and 6.
Step-by-step explanation:
There are 4 different grades represented, so for the first question, there are 4 ways that the students can sit if they must sit together by grade.
For the second question, there are 3 grades other than senior level, so it starts with 3 ways that the students can be seated. 3 ways x 2 students per way = 6 ways
Answer:
2
Step-by-step explanation:
Answer:
See below ↓
Step-by-step explanation:
19.
20.
Answer:
57
Step-by-step explanation: