Question

A $642,000 property is depreciated for tax purposes by its owner with the straight-line depreciation method. The value of the building, y, after x months of use is given by y = 642,000 − 1800x dollars.

After how many months will the value of the building be $420,600?

Answer 1

`123` months

Explanation:

The value of the building y, after x months of use is given by the equation is

`y=642,000-1800x`

To find the number of years that will pass before the value of the building is $420,600, we need to equate the equation to 420,600 and solve for x.

`642,000-1800x=420,600`

Group the similar terms:

`-1800x=420,600-642,000`

Simplify the left hand side to get:

`-1800x=-221,400`

Divide both sides by -1800

`x=(-221,400)/(-1800)`

`123`

The number of months is
`123` months