Answer:
Step-by-step explanation:
Substitute the value of 
Relations are functions if every input has exactly one output
So, the first on is a function because each x value has one y value. Meaning, for example, (3,2), 3 is the x value, which is the input, and 2 is the y value which is the output. But within that set of relations, 3 only has one output which is 2.
The second one is not a function because 2 has 2 outputs. (2,3) and (2,5). 2 has an output of 3 and 5. Every input can only have one output. So this isn't a function
The third one isn't a function because 6 has two outputs. (6,3) and (6,6). 6 has two outputs of 3 and 6, so it's not a function
The last one isn't a function either because 6 has two outputs. (6,8) and (6,4). 6 has the outputs of 8 and 4. So, it is not a function
Hope that helps :)
alligators:
x = total number of alligators
n = number of years
x=20x1.25^n
crocodiles:
y = total number of crocodiles
n = number of years
y=25+10n
