Take a look at the image below.
Answer:

Step-by-step explanation:
The amount formula in compound interest is:

where:
P = principal amount
r = annual interest
n = number of compounding periods
t = number of years
We already know that:
P = $2000

t = 7 (number of years from 6th to 13th bday)
n = 4 (quarterly in a year)
Then,

You can prove the proofs by showing your work to prove the proofs.
Answer:
see below
Step-by-step explanation:
The formula for the amount resulting from P earning interest at rate r continuously compounded is ...
A = Pe^(rt)
for P=2500 and r=0.12, this becomes ...
A = 2500e^(0.12t)
Answer:
C) 75 + 50x = 25 + 70x
Step-by-step explanation:
ABC Tech:
$50 an hour. So,for x hours= 50 * x = 50x
Service charge = 75 + 50x
Tech Squad:
$70 an hour. So,for x hours= 70 * x = 70x
Service charge = 25 + 70x
C) 75 + 50x = 25 + 70x
50x - 70x = 25 - 75
-20x = -50
x = -50/-20
x =5/2 = 2
hours