Answer:
There are 36 European Butterflies
Explanation:
Step 1: Find the number of South American Butterflies
6:4 will be turned into 72:x
Divide 72 by 6 and we get 12
Multiply 12 by the 4 in the ratio 6:4 and we get 48
= 72 North American Butterflies : 48 South American Butterflies
Step 2: Find the number of European Butterflies
4:3 can be turned into 48:x
We can do the same procedure we did on Step 1
Divide 48 by 4 and we get 12
Multiply 12 by the 3 in the ratio 4:3 and we get 36
= 48 South American Butterflies : 36 European Butterflies
(Note: This formula cannot be used in all ratios because this is a shortcut I use in my head for easy ratios like this one where everything can get divided equally by everything. Also feel free to point out any mistakes.)