To calculate the total amount of money you will pay back after borrowing $80 for 5 years at an annual interest rate of 15%, we can use the formula for simple interest:
\[ \text{Total Amount} = P + I \]
where:
- \( P \) is the principal amount (the initial amount borrowed),
- \( I \) is the interest.
First, let's calculate the interest \( I \):
\[ I = P \times r \times t \]
where:
- \( r \) is the annual interest rate (in decimal form),
- \( t \) is the time in years.
For this problem:
- \( P = 80 \)
- \( r = 15% = 0.15 \)
- \( t = 5 \)
Now we can substitute these values into the formula for interest:
\[ I = 80 \times 0.15 \times 5 \]
Now calculate \( I \):
\[ I = 80 \times 0.15 = 12 \]
\[ I = 12 \times 5 = 60 \]
So, \( I = 60 \).
Now, we calculate the total amount to be paid back:
\[ \text{Total Amount} = P + I = 80 + 60 = 140 \]
Therefore, the total amount of money you will pay back after 5 years is $140.