Answer:
a) 
b) 
c) term number 17 is the one that gives a value of 40
Step-by-step explanation:
a)
The sequence seems to be arithmetic, and with common difference d = 3.
Notice that when you add 3 units to the first term (-80, you get :
-8 + 3 = -5
and then -5 + 3 = -2 which is the third term.
Then, we can use the general form for the nth term of an arithmetic sequence to find its simplified form:

That in our case would give:

b)
Therefore, the term number 20 can be calculated from it:

c) in order to find which term renders 20, we use the general form we found in step a):

so term number 17 is the one that renders a value of 40
Complete Question
It takes 28minutes for 7 people to paint 7 walls. How many minutes does it take 14 people to paint 14 walls?
Answer:
28 minutes
Step-by-step explanation:
It takes 28minutes for 7 people to paint 7 walls.
Hence, the today number of minutes for 1 person to paint the wall =>
7 people = 28 minutes
1 person = 28 minutes × 7 people =
198 people minutes = 7 walls
1 wall = 198 /7
1 wall = 28 people minutes
How many minutes does it take 14 people to paint 14 walls?
From the above calculation,
1 wall = 28 people minutes
14 walls =
= 14 walls × 28 people minutes/14 People
= 28 minutes
Therefore, it would take 28 minutes for 14 people to paint 14 walls.
If you're asking for the number, then it's 483.12