i NEED HELP IMMEDIATELY

Question

A company manufactures and sells mini-recorders. A survey of office supply stores indicated that at a price of $88 each, the demand would be three hundred recorders, and at a price of $38 each, the demand would be eight hundred recorders. If a linear relationship between price and demand exists, which of the following equations models the price-demand relationship?

(Let x represent the price per mini-recorder and y represent the demand in hundreds.)

 A. 

 B. 

 C. 

 D. 

Answer 1

The tricky part of this problem is in the very last sentence in parenthesis. Note that y represents the demand in hundreds. The methodology is straight forward once you realize this. Our answers are given in slope intercept form, y = mx + b.

m = slope = (change in y) / (change in x) = (8 - 3) / (38 - 88)

m = (5) / (-50)

m = -1/10

Now, we can use either of our two points (88, 3) or (38, 8) to solve for b.

3 = -1/10*(88) + b

3 = -44/5 + b

15/5 = -44/5 + b

b = 59/5

Therefore, y = (-1/10)*x + 59/5, (b)

(Showing how we could use the other data point to arrive at the same b)

8 = -1/10*(38) + b

8 = -19/5 + b

40/5 = -19/5 + b

b = 59/5

Answer 2

m = (300 - 800) / (88 - 38)

m = -500 / 50

m = -10

y = -10x + b

300 = -10(88) + b

300 = -880 + b

1180 = b

D. would be the correct choice if b were 1180

Can you solve for b and answer?