77(7) = 539, the total points of all her tests
539 - 18 + 81 = correct total points = 602
602/7 = 86 which is the new average
X=0 because when you have something to the power of zero your answer is 1.
x=0 since 1 to the power of zero equals 1.
hope im not too late
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:
There is not enough information for this problem, can you provide more information?
Step-by-step explanation: