If your looking for a simplified answer, it would be

.
Hope this helps.
Answer:
= - 5n - 2
Step-by-step explanation:
There is a common difference between consecutive terms, that is
- 12 - (- 7) = - 17 - (- 12) = - 5
This indicates the sequence is arithmetic with n th term
= a₁ + (n - 1)d
where a₁ is the first term and d the common difference
Here a₁ = - 7 and d = - 5, then
= - 7 - 5(n - 1) = - 7 - 5n + 5 = - 5n - 2
Answer: 25 tables.
Step-by-step explanation:
5 • 10*2= 500 (10*2= 100, then 100 times 5)
2 • 10*1= 20 (10*1= 10, then times 2)
Therefore a cafeteria can seat 500 students. Each table had 20 seats.
Divide 500/20 and get 25.
Hope this helps