2:1
Explanation:
So first you want to lay down all the information by writing down the number of gorillas and orangutans at Westside Zoo (6,4)
Next you want to write down the number of gorillas and orangutans at Central Zoo (4,3)
Now we want to put them in a subtraction like-form of equation
6-4 4-3
Now we take the remaining values and that's our answer for the ratio to gorillas and orangutans (2:1)
-Hope this helps!