Capital Gains ? What could I expect to pay, how to calculate ?

[Deanna McCormick]

I have a property I manage for a trust, that will sell for lets say 400 k

At the time of first grantors death the property was appraised at 325 K.

At the time of second grantors death the property was appraised at 375 K

difference between those dates of death is 50 k 

and difference between the last appraisal of 375 and selling price 400 is 25 K.

I don't understand how the stepped up basis works, if the trust is in the 28% tax bracket what the expected capitol gains tax is based on. 

Would it be the paid on the 50K difference between the 2 grantors ?