Inherited home from my grandmother

Your basis in the property is the value at grandmother's date of death. Add to that whatever you put into it (so 30K). Was 30K split equally between the two of you?

Sale price less basis less selling costs is your gain. Will be long term capital gain.

This assumes you haven't been renting out the house or living in it since she died.

Like was said earlier, the basis of the house is the estimate value at time of death. So Selling Price - Stepped up basis = Taxable income. In most cases if you sell in a short amount of time there is no taxable event