To compute the gain on this sell, or the loss, you must first know what your BASIS in the property is. Generally your basis is the purchase price but when you acquire propery in other ways besides purchase then you must look at different factors.
Your basis in property you inherit from a decedent is generally one of the following:
The FMV of the property at the date of the individual's death.
The FMV on the alternate valuation date if the personal representative for the estate chooses to use alternate valuation.
The value under the special-use valuation method for real property used in farming or a closely held business if chosen for estate tax purposes. This method is discussed later.
The decedent's adjusted basis in land to the extent of the value excluded from the decedent's taxable estate as a qualified conservation easement. For information on a qualified conservation easement, see the instructions to Form 706.
If a federal estate tax return does not have to be filed, your basis in the inherited property is its appraised value at the date of death for state inheritance or transmission taxes.
Now, when you show this sale you will have a basis to begin with against the sales price.
I hope this is helpful to you, but, please let me know if you need more clarification on this subject.