Simple interest can be calculated as
![A=P(1+rt)](https://img.qammunity.org/2023/formulas/mathematics/high-school/cq9n3xjp7mzdthgt3k38triptucqu3enep.png)
Where
A is the accrued amount (final amount)
P is the principal amount
r is the interest rate expressed as a decimal value
t is the time period
You have to calculate the interest rate of the loan Gil borrowed.
First step is to write the equation for r
![\begin{gathered} A=P(1+rt) \\ (A)/(P)=1+rt \\ (A)/(P)-1=rt \\ ((A)/(P)-1)\cdot(1)/(t)=r \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/high-school/6ujh8333k4bvo216lh6x1dhnvloomcbvnr.png)
For
A= $10280
P=8000
t=6
![\begin{gathered} r=((10280)/(8000)-1)\cdot(1)/(6) \\ r=0.0475 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/high-school/3tdhzkly51kx4r290t6rny2czpu3pkmw2g.png)
The interest rate is 0.0475, if you multiply it by 100 you get that it is 4.75%
To calculate the Interest, you have to subtract the money he borrowed (P) from the money he payd (A)
![\begin{gathered} I=A-P \\ I=10280-8000 \\ I=2280 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/high-school/awrtygpvj1jqrgbr8ampptnc3074tjgvc4.png)
So he will pay $2280, which corresponds to an interest rate of 4.75%