Answer
$ 8.476\%$
Work Step by Step
The interest on the loan (without the fee) is
$INT=PV(rt)=7000\times 0.08\times 3=\$ 1680$
With the additional fee of $\$ 100,$ it becomes $\$ 1780$
With this new interest, we find r from
$INT_{new}=PV(rt)$
$1780=7000(r\cdot 3)$
$1780=21,000r\quad/\div 21,000$
$ r=\displaystyle \frac{1780}{21,000}\approx$0.0847619047619
$ 8.476\%$
