Answer:
385 cards
Step-by-step explanation:
First, find 40% and 25% of 1100.
2/5 * 1100
2200/5 = 440 cards dated before 1970
1/4 * 1100
1100/4 = 275 cards dated between 1970 and 2000
Then add the two amounts together.
440 + 275 = 715 cards between pre-1970 and 2000
After that, subtract your new sum from 1100.
1100 - 715 = 385 cards after 2000
(Or to make it easier, just find 35% of 1100.)