Answer:
a) $1,920
b) $9,920
Step-by-step explanation:
Step 1. Gather all of the information.
The amount borrowed will be the principal or starting amount P:

The interest rate will be r:

We will need the interest rate in decimal form, for that, divide the percentage amount by 100:

And the time of the loan is 6 years, this will be the value of t:

Step 2. To solve part a, we use the following formula to calculate the interest:

Substituting all of the known values:

The result is:

The total interest that Karen will have to pay is $1,920.
Step 3. To solve part b, we need to find the total repayment amount.
To find this, we add the interest and the principal amount:

Where T represents the total amount.
Substituting P and I:

The total amount she will have to repay is $9,920.
Answer:
a) $1,920
b) $9,920