IF formula for depreciation

[Ohheyydeb]

I am working on a project for calculating depreciation and having trouble changing my formula for depreciation expense to an IF formula. I understand that the test should be for book value > salvage value so depreciation is allowed. I am unsure as to how to put all of this into a working formula.

My original formula for straight line dep. expense is =SLN($D$1,$D$2,$D$3.

How do I go about changing this to an IF formula?

 

[dUBBINS]

=IF(TEST, DO if TRUE, DO if FALSE)

Say your book value is in A1, and your salvage value is in B1, and if the book value is greater you want it to use your formula, and if not, then do nothing:

=IF(A1>B1,SLN($D$1,$D$2,$D$3),"")