Bob is cold. Bob is rough. Bob is round. Dave is blue. Dave is cold. Dave is not white. Fiona is cold. Fiona is not red. Fiona is not rough. Fiona is white. If Dave is red and Dave is blue then Dave is not round. If Bob is not blue then Bob is young. All white people are young. If someone is blue and young then they are round. Red people are not round. If Fiona is blue and Fiona is cold then Fiona is young.
Dave is not blue.