Question 849517:  A manufacturing company finds that they can sell 300 items at $2.00 per item and 175 items at $2.50 per item. If the relationship between the number of items sold x and the price per item p is a linear one:
 
Find a formula that gives x in terms of p: x=_____ 
Now use the formula to find the number of items they will sell if the price per item is $1.50.  
They will sell___items if the price is $1.50. 
 Answer by Theo(13342)      (Show Source): 
You can  put this solution on YOUR website! y = number of items sold. 
x = price per item.
 
 
when x = 2, y = 300 
when x = 2.5, y = 175
 
 
(x1,y1) = (2,300) 
(x2,y2) = (2.5,175)
 
 
slope = (y2-y1) / (x2-x1) = (175-300) / (2.5-2) = -125 / .5 = -250
 
 
point slope form of equation of a straight line is y-y1 = m(x-x1)
 
 
m is equal to -250 
let x1 = 2 and y1 = 300 
equation becomes: 
y-300 = -250(x-2) 
simplify to get: 
y-300 = -250x + 500 
add 300 to both sides of this equation to get: 
y = -250x + 800
 
 
that's your equation.
 
 
y = -250x + 800
 
 
when x = 1.5, this equation becomes:
 
 
y = -250(1.5) + 800 which becomes: 
y = -375 + 800 which becomes: 
y = 425
 
 
 
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