After 4 days work together. C stopped work.
1 day complete 59/720 of the job.
4 days complete 236/720 of the job.
Left 1-236/720 = 484/720 of the job.
When A and B work together,
1 day complete 44/720 of the job
So,
11 days to complete the 484/720 of job.

I assumed C rest for 11 days.
As question want the whole number of days when A and B work together.

This question have grey areas to assume.
May I ask, where your get this question from?

Thank you very much.

Thank you