Using an arithmetic sequence, we have that:
a) The formula is: ![a_n = 149 - 6(n - 1)](https://tex.z-dn.net/?f=a_n%20%3D%20149%20-%206%28n%20-%201%29)
b) With n = 8, we have that 107 bars were sold in the eight week.
<h3>What is an arithmetic sequence?</h3>
In an arithmetic sequence, the difference between consecutive terms is always the same, called common difference d.
The nth term of an arithmetic sequence is given by:
![a_n = a_1 + (n - 1)d](https://tex.z-dn.net/?f=a_n%20%3D%20a_1%20%2B%20%28n%20-%201%29d)
In which
is the first term.
Given the table, the first term and the common difference are, respectively, given by:
.
Hence the equation is:
![a_n = 149 - 6(n - 1)](https://tex.z-dn.net/?f=a_n%20%3D%20149%20-%206%28n%20-%201%29)
Then, the number of sales in the 8th week is given by:
![a_8 = 149 - 6(8 - 1) = 107](https://tex.z-dn.net/?f=a_8%20%3D%20149%20-%206%288%20-%201%29%20%3D%20107)
Mopre can be learned about arithmetic sequences at brainly.com/question/6561461
#SPJ1