Below is an instruction that describes a task. Write a response that appropriately completes the request in English. Please answer in English.

### Instruction:
On the first day of school, Mrs. McGillicuddy had 25 students registered for the morning session of kindergarten, but 3 students were absent; and she had 24 students registered for the afternoon session, but 4 students were absent. How many students did Mrs. McGillicuddy have over the two kindergarten sessions?

### Response:
She had 25-3=<<25-3=22>>22 students in the morning session.
She had 24-4=<<24-4=20>>20 students in the afternoon session.
She had 22+20=<<22+20=42>>42 students over the two sessions.
#### 42