Question 1043290
<pre><b>
When 0 years had passed since the lamp was bought, 
it was worth $240.

When 6 years had passed since the lamp was bought, 
it was worth $60.

Let x = the number of years that had passed since
the lamp was bought.

Let y = the dollar amount that the lamp was worth 
when x years had passed.

Then when x = 0, y = $240

And when x = 6, y = $60.

So this is the same as the problem:

Find the equation of the line that passes through
the points

(0,240) and (6,60)

{{{m=(y[2]-y[1])/(x[2]-x[1])=(60-240)/(6-0)=(-180)/6=-30}}}

{{{y-y[1]=m(x-x[1])}}}

{{{y-240=-30(x-0)}}}

{{{y-240=-30x}}}

{{{y=-30x+240}}}

Edwin</pre></b>