For this case we have that each student takes 8 \ frac {3} {4} minutes to perform and play 3 songs. Then, we convert the mixed number to a fraction:

Thus, each student takes
minutes.
If there are 9 students in the recital then we have:
minutes.
Thus, the recital lasts at least 78.75 minutes.
Answer:
The recital lasts at least 78.75 minutes.