Answer:
Step-by-step explanation:
Hello, please consider the following.

So this is divisible by 3.
Now, to prove that this is divisible by 9 = 3*3 we need to prove that
is divisible by 3. We will prove it by induction.
Step 1 - for n = 1
4+17=21= 3*7 this is true
Step 2 - we assume this is true for k so
is divisible by 3
and we check what happens for k+1

is divisible by 3 and
is divisible by 3, by induction hypothesis
So, the sum is divisible by 3.
Step 3 - Conclusion
We just prove that
is divisible by 3 for all positive integers n.
Thanks
Answer: B) 684m
Step-by-step explanation:
From 9 to 27 is a 3 times increase, from 27 to 108 is a 4 times increase. So following the pattern, we can determine that it will increase 5 times, and fall another 540m in second 4. Then, we simply add all the numbers together to get the answer!
20 * (31/100) = 21*0.31=6.51
20.00-6.51=13.49
Caleb paid $13.49