Answer:
Part 1) The exponential function is equal to 
Part 2) The population in 2010 was
Step-by-step explanation:
Part 1) Write an exponential decay function that models this situation
we know that
In this problem we have a exponential function of the form

where
y ----> the fish population of Lake Collins since 2004
x ----> the time in years
a is the initial value
b is the base
we have


substitute
----> exponential function that represent this scenario
Part 2) Find the population in 2010
we have
so
For 
substitute
Answer:
50 feet
Step-by-step explanation:

Hope this helps!
K = Kevin's age
D = Daniel's age
K = 3D
K - 4 = 5(D - 4)
Plug in 3D for the K values in the second equation.
3D - 4 = 5(D - 4) Use the Distributive Property
3D - 4 = 5D - 20 Add 4 to both sides
3D = 5D - 16 Subtract 5D from both sides
-2D = -16 Divide both sides by -2
D = 8
Now, plug that D value into the original equation.
K = 3D Plug in the D value
K = 3(8) Multiply
K = 24
Finally, you can double check your math.
4 years ago, Daniel would've been 4 and Kevin would be 20, so Kevin would've been 5 times as old as Daniel. And 8 x 3 = 24.
So, Kevin is 24.