SOLUTION: the science company finds out that when it sells systems for $1200 each, they sell 70 systems per month. when the price drops to $1100, they sell 75 systems per month. let x be

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Question 513652: the science company finds out that when it sells systems for $1200 each, they sell 70 systems per month. when the price drops to $1100, they sell 75 systems per month.
let x be the number of systems sold and y be the selling price. write an equation for a line that relates the sales to the price.

Answer by Sarpi(32) About Me  (Show Source):
You can put this solution on YOUR website!
Let x be the number of systems sold = Quantity
Let y be the selling price = Price
x y
70 1200
75 1100
Step 1:
Finding the slope, m = %28Y1-Y%29%2F%28X1-X%29
= %281100-1200%29%2F%2875-70%29
= -20
Step 2:
Find the equation of the line; y= mx+c
if x=70 and y=1200 then c?
1200 = -20(70)+c
1200 = -1400 + c
1200+1400 = c
c = 2600
Finally;
The equation is y = -20x+2600