Answer:
hope this helps :)
Step-by-step explanation:
I see this as a basic equation.
If she starts at point x, 8 feet, then goes down another 13, she is adding to the number of feet she traveled down.
So your answer would be 8+13=21
If this isn't what you needed, because I am not sure what math you are taking, let me know if I can help you more!
The formula of the Simple Interest is:
I=PRT
P for Principle Amount ($1200)
R for Rate (5%=

= 0.05)
T for Time in years (4 years)
I = 1200 × 0.05 × 4
= $240
Add the interest to the principle amount to check the balance
$1200 + $240 = $1440