Question

Suppose that a sales person observes that if an item is priced at $9 per item then 6 items are sold. If 4 items are sold for $11 per item then find a linear equation to model the number y of items sold for x dollars per item. Find the slope-intercept form of the equation of the line.

Answer 1

Answer:

y = -x + 15

Step-by-step explanation:

if an item is priced at $9 per item then 6 items are sold.

Thus, the input is 9 while the output is 6.

Thus, we can say; x, y = (9, 6)

4 items are sold for $11 per item. Thus, the coordinate is; (11, 4)

Now,slope is;

m = (y2 - y1)/(x2 - x1)

m = (4 - 6)/(11 - 9)

m = -2/2

m = -1

We know that slope intercept form is;

y = mx + c

Let's try the first point.

Thus;

6 = -1(9) + c

6 + 9 = c

c = 15

Thus, equation of line is;

y = -x + 15