Answer:
42
Step-by-step explanation:
This can be done with a Venn diagram, but I can't draw it here, so I'll explain it.
Of the 42 new ones, 3 are also his favorite. That means there are 39 new that are not favorite.
Of the 19 favorites, 3 are also new, so 16 are favorite but not new.
New but not favorite: 39
Favorite but not new: 16
New and favorite: 3
Total above: 39 + 16 + 3 = 58
He has a grand total of 100 toy cars, so 100 - 58 = 42
42 are neither new nor favorite.
