48 cards 1:1 mean there are 24 red cards and 24 black cards
8 red cards are removed Donnie you have 24-8 = 16 red cards and 24 black cards
The ratio of red to black would be 16:24 both numbers are even and are dividable by 8 :
16:24 simplifies to 2:3
The new ratio is 2:3
