Catherine found that as she increases the price of a chocolate bar, the number of sales per week decreased.
week - number of sales
1 - 149
2 - 143
3 - 137
4 - 131
5 - 125
a. write a formula for the arithmatic sequence that represents the number of sales per week.
b. exlain how you could use the information to predict the number of sales for the eighth week.

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step-by-step explanation:

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20

step-by-step explanation:

a 4/6 = 9/12   not proportional

step-by-step explanation:

to find which are not proportional, we can use cross products

if it is true, they are proportional.   if it is not true, they are not proportional.

a 4/6 = 9/12

4* 12 = 6*9

48 = 54

not this is not proportional  

b 2/3 = 12/18  

2* 18 = 3 * 12

36 = 36

this is proportional

c 5/4 = 10/8  

5*8 = 4*10

40 = 40

this is proportional

d 7/5 = 35/25

7*25 = 5 * 35

175 = 175

is proportional

3+3+3+2*2*2+29*12 = 365

step-by-step explanation: