I think the boxes must be filled with
1/3 and -1/5.
Answer:

Step-by-step explanation:
<h2>This account can be modeled using the compound interest formula.</h2><h2>the compound interest formula is expressed as</h2>

Where
A =final amount = y
P=initial principal balance
= $300
r=interest rate = 16%= 0.16
t=number of time periods elapsed= x
Hence the equation to model his account balance/ final amount A (y) after time (x) years is

Answer:
The value of x + y is -16.
Step-by-step explanation:
If each term is calculated by multiplying the previous one times 5 and then subtracting 20 from that result, then we can use that information to relate the first term (x) and the second one (0).
Following the info above, the following equation applies:
0 = 5 x - 20
then we solve for x:
5x = 20
x = 20/5
x = 4
Now we do the same study relating the second term (0) and the third one (y):
y = 5 (0) - 20
y = -20
Now that we have the value for both unknowns, we can estimate what they ask you: The value of x + y:
x + y = 4 + (-20) = 4 - 20 = -16