keep getting part B wrong

Derek receives a duplex as a gift from his uncle. The uncle's basis for the duplex and land is $120,000. At the time of the gift, the land and building have FMVs of $60,000 and $90,000, respectively. No gift tax is paid by Derek's uncle at the time of the gift. To determine gain, what is Derek's basis for the land? To determine gain, what is Derek's basis for the building? Will the basis of the land and building be the same as in Parts a and b for purposes of determining a loss? Requirement a. To determine gain, what is Derek's basis for the land? (Do not round intermediary calculations. Only round the amount you input in the cell to the nearest dollar.) To determine gain, Derek's (the donee's) basis for the land is $ 48,000. Requirement b. To determine gain, what is Derek's basis for the building? (Do not round intermediary calculations. Only round the amount you input in the cell to the nearest dollar.) To determine gain, Derek's (the donee's) basis for the building is $