Answer:
69
Step-by-step explanation:
you add the nubers then subtract th 7
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.
Pythagorean theorem a^2+b^2=c^2
In an arithmetic sequence, the difference between consecutive terms is constant. In formulas, there exists a number
such that

In an geometric sequence, the ratio between consecutive terms is constant. In formulas, there exists a number
such that

So, there exists infinite sequences that are not arithmetic nor geometric. Simply choose a sequence where neither the difference nor the ratio between consecutive terms is constant.
For example, any sequence starting with

Won't be arithmetic nor geometric. It's not arithmetic (no matter how you continue it, indefinitely), because the difference between the first two numbers is 14, and between the second and the third is -18, and thus it's not constant. It's not geometric either, because the ratio between the first two numbers is 15, and between the second and the third is -1/5, and thus it's not constant.
Well, basically there are
acute angle, right angle, obtuse angle ..
and also we use concurrent angles, corresponding angles, alternate angles, vertically opposite angles,..
..hope it helped a bit