College Math Problem

Question

An​ e-reader manufacturer expects to sell

60​,000

units each year if the selling price is

​$220.

If the selling price is reduced to

​$170​,

then the manufacturer expects to sell

130​,000

units each year.

a. Assume that the relationship between selling price​ ($) and units sold​ (1000s) is linear. Find the equation of the line that describes this relationship. Write your answer in​ slope-intercept form. Let x represent the selling price and y represent the units sold​ (1000s).

Answer 1

Slope formula (y2-y1) / (x2-x1)

so since x is selling price & y is amount in 1000s,

(130-60) / (170-220)

= 70/-50

Slope = -1.4

y intercept

y=mx+b

60=-1.4(220)+b

60=-308+b

368=b

y= -1.4x + 368

Answer 2

Slope formula (y2-y1) / (x2-x1)

so since x is selling price & y is amount in 1000s,

(130-60) / (170-220)

= 70/-50

Slope = -1.4

y intercept

y=mx+b

60=-1.4(220)+b

60=-308+b

368=b

y= -1.4x + 368