Question 164053
ok, the first thing we need is to find the formula:

The problem says that the formula is linear so let's use the slope-intercept form or y=mx+b where m=slope and b=the y-intercept.

Remember that the slope is simply how much y changes for each unit of x.  So in this situation when x moves from 1999 to 2001 the y changes from 30,000 to 26,000. 
Formula: slope=(change in y)/(change in x)
or
{{{slope=(y1-y2)/(x1-x2)}}}
or
{{{slope=(30000-26000)/(1999-2001)}}}
{{{slope=4000/-2}}}
{{{slope=-2000}}}
So in this case x changed 2 and y changed -4,000, so to find out the change per year instead of per 2 years: divide -4000 by 2 and you get the change in y divided by the change in x or -2000
now we know that y=-2000x+b
the y-intercept or "b" is the y value when x=0 and x is the number of years passed since the beginning of 1999 so when x=0 y=30,000
therefore our formula is {{{y=-2,000x+30,000}}}

Part 2
Find the value of the asset in the year 2006:
2006-1999=7
so find the value of y when x=7
y=-2000(7)+30000
y=-14000+30000
y=16000

Part 3
Find after how many years the value of the asset will be $7,000.
let y=7000 and solve for x
7000=-2000x+30000
subtract 30000 from each side
-23000=-2000x
divide each side by -2000
11.5=x
so the value of assets will be $7000 after 11.5 years

Part 4
Find after how many years wil the asset be worthless(value=0)
let y=0 and solve for x
0=-2000x+30000
subtract 30000 from both sides
-30000=-2000x
divide each side by -2000
15=x
so the value of assets will be worthless after 15 years
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I hope this helps
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