Answer: 14a. an = 149 -6(n -1) 14b. Evaluate the formula with n=8. 15. (no question content)Step-by-step explanation:14. Each week, sales decreases by 6, so the arithmetic sequence for sales has a first term of 149 and common difference of -6. The general formula for the n-th term is ... an = a1 + d·(n -1) . . . . . . where a1 is the first term, d is the common differencePutting the numbers for this sequence into the general formula, we get ... an = 149 -6(n -1)__To predict the sales for the 8th week, put n=8 into the formula and do the arithmetic. a8 = 149 -6(8-1) = 107 . . . . predicted sales for week 8_____15. The graph is shown attached. There is no question content.